Horse and Livestock Evacuation Load Calculator: A Supply Range You Can Compute, and a Weight Worksheet You Take to a Scale

Compute the supplies, but weigh the rig. Water and feed can be worked out in advance from per-head figures that extension services publish, and they come as ranges, not single numbers. Trailer and truck weight cannot be worked out from head counts. EPA’s towing worksheet and University of Maryland Extension both call for a scale reading of the loaded rig, so this page ends in a worksheet you take to a scale, not a pass-or-fail answer.

What this page does and does not do

Part one is a supply calculator: body weight, species, and days in; gallons and pounds out, as a range across named sources. Part two is a weight worksheet: sixteen lines and ten comparisons from EPA’s own form, some read off your labels and the rest taken from the loaded rig at a scale. A green light against a weight rating built on an estimate could put an overloaded trailer on an evacuation route, so the worksheet ends in readings, not a verdict.

The page does not print a go or no-go verdict, because the sources call for a scale reading. It does not say how many trips you get (the evacuation vehicle load planner covers that), and it publishes no towing law: brake thresholds, license classes, and legal load limits are state vehicle code. See the two-vehicle evacuation convoy and rural pet evacuation with no second vehicle pages. Manufacturer ratings and federal labeling rules are a different category.

For when to go and how many days to plan, see horse and livestock evacuation basics. If the animals cannot be hauled, see releasing livestock when you cannot load them.

Part one: the supply calculator

Step 1: get the body weight

Water and feed figures are both functions of body weight. University of Tennessee Extension publication SP795 opens with the problem: “Estimates of a horse’s weight made by owners are often under- or overestimated by as much as 150 pounds.” On a 1,000 pound horse that is a fifteen percent error before you multiply by days.

SP795 says a scale is ideal. Without one, it prints an equation and says heart girth plus body length tends to be more accurate than heart girth alone. Feed-store weigh tapes do not account for horses with a longer or shorter body than average.

The equation: heart girth in inches, times heart girth in inches, times body length in inches, divided by 330, gives pounds. SP795’s worked example (70 inch girth, 78 inch length) gives 1,158 pounds.

The scope travels with it. SP795 says the equation is meant for mature, non-pregnant, light breed horses, and is not recommended for draft or warmblood types, miniatures, growing horses, or pregnant horses. For those, use a scale.

To measure, stand the horse square on flat ground. Heart girth is a tape around the midsection behind the elbow and directly behind the highest point of the withers, without causing an indent. Body length runs from the point of the shoulder to the point of the buttock, tape flat along the body. SP795 says to measure at the same time of day, preferably before morning feeding. Write the number on the stall card, and the supply arithmetic takes two minutes.

For cattle, sheep, and swine, the published tables are keyed to weight classes, so a class estimate is what they ask for.

Step 2: water, published as a range

A calculator would mislead you here if it picked one figure. Three publishers give five daily water figures for a horse, differing by roughly three to one. None is wrong, because they answer different questions.

Source	Published figure	Scope the source states
Ohio State University Extension, AS-H-10-24	50 mL/kg BW/day (0.006 gal/lb BW/day), worked as 6.6 gal (25 L) per day for an 1,100 lb horse	An idle adult horse in thermoneutral conditions, as an average. OSU adds that horses on mostly dry hay drink more than horses on pasture. An evacuated horse is usually on hay, so in our reading this row is a floor
Ohio State University Extension, AS-H-10-24	1.3 gal per 100 lb of body weight (13 L per 100 kg)	Idle horses on hot days; they drink more when exercised
NDSU Extension, AS1763 (Revised February 2026)	8.2 gal/day at 68 degrees F; 12.7 at 86 degrees F; 11.1 at minus 4 degrees F	A mature idle horse of 1,102 lb; adapted from NRC’s Nutrient Requirements of Horses, Sixth Revised Edition, 2007
NDSU Extension, AS1763	10.8 gal/day at 68 degrees F; 21.7 at 95 degrees F	A mature horse of 1,102 lb at moderate activity, same NRC source
UF/IFAS Extension, VM252	At least 10 to 12 gallons of clean water per horse per day	Written for equines in natural disasters as a staging figure

UF/IFAS’s 10 to 12 gallons is what to have on hand, not what the horse necessarily drinks, and NDSU moves the same horse from 8.2 to 21.7 gallons by changing only temperature and activity.

Temperature is the practical finding. The gap between NDSU’s 68 degree and 95 degree rows for the same horse is 10.9 gallons per day. For three horses over five days that is 163 gallons, about 1,360 pounds of difference in what you tow, decided by the weather. If your day is hot and the horses will work, plan against the hot row and name it.

Do not average these figures. An average describes no animal in no conditions. If you need one number, take the highest figure whose stated scope matches your conditions and write the source beside it. Age, pregnancy, lactation, diet, and illness all change how much a horse drinks, so ask your veterinarian about yours.

Other species

NDSU AS1763 tabulates the other species and opens with the reason it matters: “A 10% loss of body water is fatal to most species of domestic livestock.” The tables below follow its values. Where NDSU prints no value, the cell is empty here too.

Beef cattle, gallons per head per day, by temperature and production (NDSU’s caption says “beef cows,” though the columns also cover growing and finishing cattle and bulls; adapted from NRC, 2016).

Temp. (F)	Growing 400 lb	Growing 600 lb	Growing 800 lb	Finishing 600 lb	Finishing 800 lb	Finishing 1,000 lb	Pregnant 900 lb	Pregnant 1,110 lb	Lactating 900 lb	Bulls 1,400 lb	Bulls 1,600 lb
40	4.0	5.3	6.3	6.0	7.3	8.7	6.7	6.0	11.4	8.0	8.7
60	5.0	6.6	7.9	7.4	9.1	10.8	8.3	7.4	14.5	9.9	10.8
70	5.8	7.8	9.2	8.7	10.7	12.6	9.7	8.7	16.9	11.7	12.6
80	6.7	8.9	10.6	10.0	12.3	14.5			17.9	13.4	14.5
90	9.5	12.7	15.0	14.3	17.4	20.6			16.2	19.0	20.6

NDSU prints no pregnant-cow value at 80 or 90 degrees, so do not interpolate one. NDSU also prints rows for 50 degrees F, which are not reproduced here.

Other horse classes (NDSU, adapted from NRC, 2007): a 661 lb yearling at moderate activity drinks 4.8 gallons a day at 14 degrees F and 5.0 at 68; at 68 degrees F, a 1,102 lb pregnant mare drinks 8.1 and a lactating mare 13.5. NDSU’s idle rows do not rise steadily with temperature, and it explains part of that by noting that horses on a fiber-rich, forage-based diet need more water than horses on a more digestible grain diet. In winter, the cold row is not the low row.

Sheep, gallons per head per day: lambs (5 to 20 lb) 0.1 to 0.3; feeder lambs (60 to 110 lb) 1.0 to 1.5; pregnant ewes (175 lb and up) 1.0 to 2.0; lactating ewes 2.0 to 3.0; rams 1.0 to 2.0.

Swine, gallons per head per day: nursery (up to 60 lb) 0.2 to 0.5; grower (60 to 100 lb) 0.5 to 2; finishing (100 to 250 lb) 2 to 3; nonpregnant gilts 3 to 5; pregnant sows 3 to 6; lactating sows 5 to 8; boars 3 to 6.

Dairy, gallons per head per day: calves (1 to 4 months) 1.3 to 3.5; heifers (5 to 24 months) 3.8 to 9.6; milking cows at 30, 50, 80, and 100 lb of milk a day 18 to 22, 23 to 27, 30 to 36, and 35 to 41; dry cows 9 to 13.

Swine warning. AS1763 says swine on a high-energy diet that are deprived of water, for example in a power outage, and then given free access again are at risk of salt poisoning (cerebral edema), and should get water sparingly until fully rehydrated. Deprived and then suddenly refilled is what happens when a trailer arrives somewhere with a hose. If a pig has gone without water, call a veterinarian before refilling freely.

Step 3: feed in pounds

The disaster publications state feed in days. UF/IFAS VM252 says to obtain a 3- to 7-day supply of feed, water, and medications for all animals on the property, with no pounds. The nutrition publications state pounds as a percentage of body weight, and they do not agree.

Source	Published intake	Basis
Utah State University Extension, Equine Nutrition: Forages	1.0 to 2.0 percent of body weight daily in forage, or 10 to 20 lb of cured or baled hay (90% dry matter) for a 1,000 pound horse	As fed
Alabama Cooperative Extension System, ANR-3153 (Revised August 2025)	2 to 2.5 percent of body weight in dry matter per day; some horses eat more than 3 percent; minimum 1 percent (usually for horses in heavy work on grain-based diets); recommended target about 2 percent	Dry matter

Part of the difference is as fed versus dry matter. Utah State also notes that pasture changes the answer: a horse eating pasture at 20 to 30 percent dry matter needs roughly 30 to 60 pounds a day for the same nutrition.

Alabama works out its 2 percent rate as 18, 20, 22, and 24 pounds a day for horses of 900, 1,000, 1,100, and 1,200 pounds, or 11, 12, 14, and 15 fifty-pound square bales over 30 days. Every pound is dry matter, not hay on a scale, and the 30-day table does not factor in wastage.

The join is ours. No publisher multiplies these percentages over an evacuation-length day count. Doing so is our reasoning, not a publisher’s recommendation:

Pounds of forage to load = body weight in pounds, times the intake percentage you chose, times the number of days you chose.

The percentages are consumption rates, not loading recommendations, and wastage is not included, so add a margin.

Weigh these yourself; none of this page’s sources publishes a weight for them. Hay bales vary with baler, moisture, forage, and tie, so put two or three of your own on a scale (Alabama’s tables assume fifty-pound bales only for conversion). Weigh the tack pile you would actually load, once, on a bathroom scale. A full water container weighs the water plus the container.

Step 4: turn gallons into pounds

Water is the load. USGS’s Water Science School reports that a gallon of tap water at 70 degrees F weighed 8.329 pounds. FMVSS No. 110 prescribes a label for motor homes that treats a full load of water as cargo at 1 kg/L (8.3 lb/gal) and says the tongue weight of a towed trailer counts as cargo. It is a labeling rule for recreational vehicles, not a requirement on your horse trailer, but it puts the point in one sentence.

Worked example: three horses, five days

Five days is an arbitrary figure chosen to sit inside the published spread, not a recommendation. We use 1,000 pounds where a source is keyed to body weight, and NDSU’s own 1,102 pound row without rescaling. The multiplication by three horses, five days, and 8.329 pounds is our arithmetic.

Basis	Per horse per day	Three horses, five days	Weight
OSU per-pound function, idle and thermoneutral (0.006 gal/lb x 1,000 lb)	6 gal	90 gal	about 750 lb
NDSU/NRC, mature idle, 1,102 lb, 68 degrees F	8.2 gal	123 gal	about 1,025 lb
UF/IFAS VM252, low end	10 gal	150 gal	about 1,250 lb
UF/IFAS VM252, high end	12 gal	180 gal	about 1,500 lb
OSU hot-day figure (1.3 gal/100 lb x 1,000 lb)	13 gal	195 gal	about 1,625 lb
NDSU/NRC, mature moderate activity, 1,102 lb, 95 degrees F	21.7 gal	325.5 gal	about 2,710 lb

The first and fifth rows apply Ohio State’s per-pound functions to a body weight we chose. Because you are loading baled hay, the first row is a floor, not a plan.

Feed basis	Per horse per day	Three horses, five days
Utah State, 1.0 percent (as fed)	10 lb	150 lb
Utah State, 2.0 percent (as fed)	20 lb	300 lb
Alabama, 2 percent target (dry matter)	20 lb	300 lb
Alabama, 2.5 percent (dry matter)	25 lb	375 lb

The two 20 lb figures are not the same quantity. Twenty pounds of dry matter is about twenty-two pounds of hay on a scale, and the pounds you load are the as-fed number. That conversion is our arithmetic.

For three horses and five days, supplies alone land between roughly 900 and roughly 3,085 pounds. Add three horses at about 1,000 pounds each and the load is 3,900 to 6,085 pounds, before the trailer, tack, buckets, or a person in the truck. A spread of more than three to one on supplies alone is the argument for the next section: no estimate made in the barn is precise enough to decide pass or fail against a rating.

Part two: the weight worksheet

Why this half is a worksheet

EPA, in the towing forms of its Health and Safety Manual, defines line 1, Gross Trailer Weight, as a scale reading of the trailer and its contents detached from the vehicle, and takes tongue weight with only the landing gear on the scale, at towing height because the attitude affects the reading. University of Maryland Extension, writing for horse owners, says it can be difficult to estimate the total weight of horses, people, and cargo, and that “It is a good idea to weigh the vehicle and trailer, fully loaded, to determine the gross combination weight of the entire rig.” It says weighing services are usually available at highway weigh stations or the local dump, and some grain farmers may allow use of their scales.

Federal Motor Vehicle Safety Standard No. 110 does not tell you to weigh anything, but it requires many trailers to carry a printed cargo capacity number, the one check here you can run without a scale. So the deliverable is a form, a source for each figure, and ten comparisons. Fill it in once with the rig loaded the way you would actually load it, and keep the sheet in the truck.

EPA Table B-1: the sixteen lines

EPA’s scope sentence travels with the worksheet: “The following analysis should be conducted by an EPA staff member who has taken the Trailer Towing Safety Course.” It is a federal agency’s internal procedure for trained staff, not a consumer instruction, and it prints no date. Use it as a template.

#	Line item (EPA’s name)	Where the number comes from	Type
1	Gross Trailer Weight (GTW)	Scale, detached from the vehicle	Measured
2	Trailer Tongue Weight (TTW)	Scale, only the jack on the pad, at towing height	Measured
3	Base Curb Weight (BCW)	Usually the vehicle owner’s manual	Published
4	Gross Vehicle Weight (GVW)	Curb weight plus passengers and equipment, or scale	Measured or derived
5	Gross Combination Weight (GCW)	Scale, whole rig, or GTW plus GVW	Measured or derived
6	Gross Axle Weight, Front	Scale, front wheels, trailer attached	Measured
7	Gross Axle Weight, Rear	Scale, rear wheels, trailer attached	Measured
8	Gross Vehicle Weight Rating (GVWR)	Owner’s manual, or the label inside the driver’s side door	Published
9	Gross Combination Weight Rating (GCWR)	The vehicle manual, or the manufacturer	Published
10	Gross Axle Weight Rating, Front	Owner’s manual, or inside the driver’s side door	Published
11	Gross Axle Weight Rating, Rear	Owner’s manual, or inside the driver’s side door	Published
12	Maximum Trailer Towing Rating (MTTR)	Owner’s manual, or inside the driver’s door	Published
13	Hitch Capacity (HC)	Often on the hitch frame	Published
14	Tow Ball Rating (TBR)	Often stamped on the tow ball	Published
15	Tongue Weight Rating (TWR)	Often on the hitch frame	Published
16	Draw Bar Tongue Rating (DBTR)	Often on the draw bar	Published

Four lines can only come off a scale: gross trailer weight, tongue weight, and the two axle weights.

University of Maryland Extension adds that a trailer’s rating is on a tag on the tongue or neck, a tow vehicle’s is on a tag inside the driver’s side door, and gross combination weight rating (vehicle, trailer, and all cargo in both, including horses, people, and tack) is listed in the owner’s manual. It warns that not all vehicles in a series share a rating, and not every half-ton truck has the same one. Its instruction is to use the owner’s manual GCWR as the final say on whether a truck-trailer combination is safe. That is why we print no tow rating for any model.

EPA Table B-2: the ten checks

Check	Passes when
GTW against MTTR	Line 1 is less than line 12
GTW against HC	Line 1 is less than line 13
GTW against TBR	Line 1 is less than line 14
TTW as a share of GTW	Line 2 is 10 to 15 percent of line 1
TTW against TWR	Line 2 is less than line 15
TTW against DBTR	Line 2 is less than line 16
GVW against GVWR	Line 4 is less than line 8
GCW against GCWR	Line 5 is less than line 9
Front axle	Line 6 is less than line 10
Rear axle	Line 7 is less than line 11

EPA’s remedies for a failed check are to reduce the weight, redistribute the load, or select other equipment. For tongue weight and rear axle failures, its first remedy is to decrease tongue weight while keeping it within 10-15% of gross trailer weight.

The rule that makes it a procedure. If any answer is no, EPA says the load must be redistributed or other equipment found, and the entire analysis must be repeated afterward, because a fix for one item can break another. Moving four hundred pounds of water forward to fix a rear axle number changes the tongue weight, which changes two other checks. Run the whole sheet again. EPA’s manual also says no towing trip can take place before the analysis and the pre-trip inspection checklist are complete. That is an internal rule for EPA staff, not a law binding you.

The rear axle is a likely failure for this load (our reasoning, not a published finding). A rig can pass its gross combination weight rating and still be over its rear axle rating. Tongue weight presses down at the ball, behind the rear wheels, and water and hay in the truck bed sit behind the rear axle. Run both axle checks, not just the totals.

The one check you can run without a scale

Section S4.3.5 of FMVSS No. 110 requires each trailer to carry, on its placard, a statement that the weight of cargo should never exceed a stated number of pounds and kilograms. The placard must be permanently affixed near the trailer’s certification label.

Here is the line. The standard applies to motor vehicles with a gross vehicle weight rating of 4,536 kilograms (10,000 pounds) or less, except motorcycles. So this check exists for a trailer rated at 10,000 pounds GVWR or less and does not reach one rated above it. We cannot tell you which side you are on, and no source here publishes typical GVWRs by trailer type. The GVWR tag on your trailer settles it. Both sides are populated: FS-955 writes its license section around towing more than 10,000 pounds, and the Mississippi State chart below runs to 18,400 pounds of cattle in a 34 by 7 trailer. A missing placard on a heavy trailer means the standard does not reach you, not that the trailer is defective.

If the placard is there, total the horses at measured weights, hay at weighed weight, water at gallons times 8.329 pounds, buckets, tack, and bedding. The total has to come in under the printed number.

What this check does not tell you:

1. Nothing about your tow vehicle. The trailer can be inside its cargo rating while the combination is over the truck’s gross combination weight rating.
2. Nothing about the rear axle or the hitch.
3. It is not a driving rule. It is about what a manufacturer must label. What you may legally tow is state law.
4. It may not exist on your trailer. Above 10,000 pounds GVWR the scale is your whole answer.

Safety margins: one published figure, and a look-alike

Neither the EPA worksheet nor FMVSS No. 110 publishes a safety margin. The only margin for live weight among this page’s sources is one sentence from University of Maryland Extension FS-955, dated 2012:

“When hauling live weight, a good rule of thumb is to not exceed 85% of the tow vehicle’s gross combination weight rating.”

FS-955’s reasoning is that animals are live cargo and their shifting weight in transit can substantially affect handling. Treat 85 percent as one extension service’s rule of thumb from 2012, not a consensus margin.

The look-alike. A Virginia Department of Wildlife Resources post dated January 26, 2022, reprinting a BoatU.S. Magazine article, says a fully loaded boat and trailer should weigh no more than 85% of tow capacity. Same percentage, different denominator: gross combination weight rating and tow capacity are different numbers on the same truck, and that article is about boats, as is its 7 to 12 percent tongue weight band.

What fits: floor area, not weight

For cattle, the limit in a stock trailer is usually square footage, not pounds. Two organizations publish head-count charts with different column definitions.

Chart one: Beef Quality Assurance

BQA’s Mature Cattle Hauling Loading Density Guidelines give head counts for 21 trailer and compartment sizes at 800, 1,000, 1,200, 1,400, and 1,600 pounds, allowing 10.4, 13, 15.6, 18.2, and 20.8 square feet per polled animal. Its stated basis is the Federation of Animal Science Societies’ 2020 guide, at 1.3 square feet per 100 lb of mature or fed cattle. BQA’s conditions: increase square feet per animal by 5% for horned cattle; total weight should not exceed the capacity of the truck or trailer, or legal load requirements; and cattle shape and frame score affect fit. Not all trailer sizes are in the chart.

Trailer size	Square feet	800 lb	1,000 lb	1,200 lb	1,400 lb	1,600 lb
16 ft x 6 ft	96	9	7	6	5	4
24 ft x 6 ft	144	13	11	9	7	6
20 ft x 7 ft	140	13	10	9	7	6
24 ft x 8 ft	192	18	14	12	10	9

A 24 by 6 and a 20 by 7 hold nearly the same number, because 144 and 140 square feet are nearly the same area. That is what an area model looks like.

Chart two: Mississippi State University Extension P2797

P2797 (2025) has its own table for 19 trailer sizes, built differently. Its columns read “Average cattle weight under, lb” (400 to 1,700 pounds), which are upper bounds, not point weights. It adds a Max column in pounds, from 6,500 for a 14 by 6 trailer to 18,400 for a 34 by 7. It gives the maximum recommended numbers of polled or dehorned cattle, and notes that fewer mature or fat cattle fit than feeder cattle.

Length x Width	600 lb	800 lb	1,000 lb	1,200 lb	1,400 lb	Max
16 x 6	12	9	7	6	6	7,400
24 x 6	18	14	11	9	9	11,100
20 x 7	18	13	11	9	8	10,800
32 x 7	29	22	17	14	13	17,300

MSU marks the Max header with an asterisk the publication does not explain, so do not assume it means what BQA’s asterisk does. What MSU prints around the table:

• Do not exceed the Gross Vehicle Weight Rating for the truck and trailer.
• “Reduce trailer stocking density by 5 percent for cattle with horns. Also be sure to reduce the number of head loaded during hot conditions.”
• Unless absolutely necessary, do not haul female cattle in the late stages of pregnancy, to reduce the risk of calving on the trailer or stress-induced premature calving. In an evacuation, “absolutely necessary” becomes a live question that MSU does not answer. Ask your veterinarian.
• The driver is responsible for knowing trailer dimensions, loading only cattle that will fit safely and humanely, and following each state’s maximum legal load limit. Give cattle room to stand, and partition the trailer when it is not full.

The heat reduction is the qualifier most likely to be dropped and most likely to matter in a summer wildfire evacuation. MSU gives no percentage for it, and BQA’s chart has no heat instruction at all.

The two charts are not interchangeable. BQA’s 1,000 pound column is for cattle weighing about 1,000 pounds; MSU’s is for cattle averaging under 1,000 pounds. Use one chart, in its own terms.

Horses. None of this page’s sources publishes a horse floor-area chart. Manufacturers publish stall dimensions for their own models, and FS-932 notes that partial partitions give the horse more room to spread its feet and balance.

On the road: stops, heat, cold, and brakes

Source	Interval published	What it is for
Ohio State University Extension, AS-H-10-24	Stop every 3 to 6 hours to offer fresh clean water	Water; OSU attributes it to Houpt and Wickens, 2014
University of Maryland Extension, FS-932	Rest approximately every 3-4 hours; offer water every 3-4 hours	Rest and water; fueling the vehicle counts as rest
University of Maryland Extension, FS-932	Beyond 18 hours, unload and stable overnight	Outer limit of a continuous haul
Mississippi State University Extension, P2797	Check cattle after two hours on the road, then every four hours	Checking cattle, not watering

Plan to the shorter horse interval and you satisfy both publishers. Points from the same sources that are easy to miss:

• A stopped trailer is a drinking trailer. Ohio State reports that horses offered water en route may still become dehydrated, and that water and feed intake are greater when the trailer is not moving (Kusunose and Torikai, 1996).
• Bring your own buckets. FS-932 says familiar containers help the horse eat and drink and reduce disease transfer from other horses.
• Offer water anyway. FS-932 says some horses will not drink while traveling but should still be offered water, which can help avoid colic or impaction.
• A hot horse gets water differently. NDSU says horses hot from exercise should have steady but controlled access to water, to prevent colic, laminitis, and tying up. In our reasoning, loading a panicking horse in smoke and heat counts as exertion. Ask your veterinarian how much and how often for your animal.

Cattle in heat. MSU tells haulers to avoid extreme heat when possible, especially between 11 a.m. and 4 p.m. If hauling in heat, avoid unnecessary stops, keep stops short and in shade, stop only in cooler parts of the day, load fewer cattle, and handle them gently. That pulls against the horse advice to stop every three to six hours, and neither publisher addresses the other. If you move both species together, decide before you reach the rest area.

Cattle in cold and ice. MSU defines extreme cold as a wind chill below 0 degrees F, which raises maintenance energy needs, is worse for wet cattle, and can be dangerous for unprotected cattle at highway speeds. Avoid unnecessary stops and deliver them as quickly and safely as possible. Then, with no hedge: “Do not haul cattle during icy conditions.” That rule is for cattle, and we do not extend it to horses. None of the horse publications cited here (FS-932, FS-955, AS-H-10-24, VM252, SP795) gives a cold or icy-conditions limit for hauling, so the silence is theirs.

Brakes. FS-932 says that any time the load changes during a trip (animals unloaded or loaded), drive a short distance and check brake operation before entering high-traffic roads, adjusting the brake controller as needed. In an evacuation you may drop two animals at one stop and carry two on, and the load your controller was set for is gone. FS-932 also says to walk around the trailer whenever the driver gets out, checking tires, lights, and the hitch.

On foot. The WALARM project (University of Wyoming Extension with Colorado State and Montana State Extension) says cattle that could normally move 15 miles may move only 2 miles in smoke or 1 mile in water. It is written for emergency managers and organized producer teams, not one owner at a gate, and its question about authority to overload a vehicle is not an invitation for an owner to exceed a rating.

License class and the commercial trap

This page publishes no towing law, since license class differs by state. One question is worth asking before an evacuation. FS-955 says most drivers hold a non-commercial class C license and gives the reassuring half first: “This license is sufficient for most two- and three-horse trailers pulled by an SUV or pickup truck for non-commercial purposes.” A class C covers a vehicle with a GVWR of 26,000 pounds or less towing a trailer with a GVWR of 10,000 pounds or less; above either you need another class. Then the catch: additional regulations apply to commercial businesses, and by federal definition an enterprise counts as commercial “if any money changes hands, even if your business does not turn a profit.” FS-955 sends that question to the reader’s state police.

Here is the evacuation version. A neighbor with a bigger trailer offers to take your two horses, and you offer a hundred dollars for fuel. That is where an owner moving their own animals can become something else to a regulator. Ask your state police or DMV before a season starts, especially if anyone will be paid, reimbursed for fuel, or hauling animals that are not theirs.

Federal motor carrier rules define a commercial motor vehicle in interstate commerce to include one rated at 4,536 kg (10,001 pounds) or more, by gross vehicle weight rating or gross combination weight rating. That definition is for the federal carrier rules, not a rule addressed to a private owner hauling to a fairground, but 10,001 pounds is lower than the phrase suggests. The definitions are usually cited to 49 CFR 390.5, but the Cornell Legal Information Institute copy records that the section was again suspended indefinitely, effective July 21, 2026 (91 FR 45661), and the operative definitions sit at 49 CFR 390.5T. Take both numbers to your state police.

Your load worksheet

Do the first half on a quiet afternoon and the second at a scale, and keep the sheet in the truck.

Before anything else

• Record every animal’s body weight, on a scale if you can. SP795’s equation is the alternative for mature, non-pregnant, light breed horses only. Write it on the stall card.
• Weigh your actual hay (two or three bales) and the tack pile you would load.
• Copy every rating onto one sheet: the trailer’s cargo capacity placard if it has one, the trailer GVWR tag on the tongue or neck, the truck’s door label GVWR and axle ratings, the owner’s manual GCWR and maximum trailer towing rating, and the hitch frame, tow ball, and draw bar stamps. A stamp is hard to read in the dark with the trailer already backed up to it.

The supply side

• Choose your day count from horse and livestock evacuation basics, match the water figure to your scope without averaging, and use a hot figure if it will be hot.
• Multiply out water for every species and convert to pounds at 8.329 per gallon. It is usually the largest line on the sheet.
• Multiply out forage at your chosen percentage, add a margin for wastage, and add medication, buckets, bedding, and the water containers themselves.

The weight side, at a scale

• Load the rig the way you would actually load it, people included, and go to a scale. Maryland points to highway weigh stations, the local dump, and, with permission, grain farmers’ scales.
• Before the first fully loaded drive, go a short distance, check the brakes, and adjust the controller. FS-932 gives its brake instruction for load changes during a trip; applying it to a first loading is our reasoning, for the same reason.
• Take the four scale readings in Table B-1: gross trailer weight, tongue weight (only the jack on the pad, at towing height), and front and rear axle weights with the trailer attached. Also take gross vehicle weight and gross combination weight so you can compare the scale with the arithmetic.
• Run all ten comparisons. The two axle checks and the six gross-trailer-weight and tongue-weight checks are where this load shape fails. If any fails, fix it and start the whole analysis again.
• If the trailer is rated at 10,000 pounds GVWR or less, run the placard check too. Passing says nothing about the truck, axles, or hitch.
• Note where you land against 85 percent of your GCWR, Maryland’s 2012 rule of thumb, which is not a consensus margin.

If you never weighed and you are leaving tonight

This section is our own reasoning, not a publisher’s. If the trailer is rated at 10,000 pounds GVWR or less, run the placard check in the barn; passing says the trailer is inside its own cargo rating and nothing about the truck, axles, or hitch. If it is rated above that, no check is available without a scale, so reduce the consumable load. Water is the heaviest and least fixed item, and a shorter first leg to a place you can refill is the lever that is entirely yours. Then weigh the rig the first calm weekend after you get home.

On the road

• Horses: stop at least every three to four hours to rest and offer water, actually stop, and carry your own buckets. Cattle: short, shaded stops in heat; deliver as quickly and safely as possible below a 0 degree F wind chill; do not haul in icy conditions.
• After any stop where animals come off or go on, drive a short distance, check the brakes, and adjust the controller before a busy road. Walk the trailer whenever you get out.
• If the haul will pass 18 hours, arrange overnight stabling in advance.
• Call a veterinarian for any animal that will not drink, arrives distressed, or was hot and hard-loaded before departure. This page gives no treatment or dosing, and no arithmetic substitutes for someone looking at the animal. This site has no veterinary reviewer.

We did not test any product, weigh any trailer, or drive any evacuation route. See our review methodology.

Where to go next

This page is the load-and-supply spoke of our pet emergency playbooks hub. For timing, day counts, and the trailer readiness list, see horse and livestock evacuation basics. For the destination, see finding a large animal evacuation center. For animals you cannot haul, see releasing livestock when you cannot load them. With no trailer or second driver, see rural pet evacuation with no second vehicle. For crates and carriers or a second vehicle, see the evacuation vehicle load planner and the two-vehicle evacuation convoy.

Then do the one thing that pays off most. Take the truck and the empty trailer to a scale this month and weigh them, then weigh them again loaded before the season starts. Two numbers, one afternoon, and the difference between running a worksheet and guessing at the gate.