The Baseline Numbers, Sourced Per Authority
Two named veterinary and animal-welfare bodies publish overlapping but not identical duration guidance. Neither is wrong; they’re just different planning targets.
| Supply |
ASPCA |
AVMA |
| Water |
At least 7 days per pet, replaced every 2 months |
At least 7 days per pet |
| Food |
7-10 days per pet (canned pop-top or dry), rotated every 2 months |
3-7 days per pet, rotated regularly |
| Medication |
2-week supply, waterproof container |
2-week supply |
Where the two disagree (food duration), 7 days sits inside both ranges, which is why the worked example below uses 7 days as the default planning target. If your storage space allows it, ASPCA’s 10-day ceiling is a reasonable stretch goal; AVMA’s 3-day floor is the absolute minimum, not a target.
Ready.gov’s baseline framing is looser: “several days’ supply” of food and water, with water amount said to vary by pet size relative to the human 1-gallon-per-person-per-day rule. Because Ready.gov’s page returned a fetch error during this research and that figure was sourced from a search-result excerpt rather than a directly confirmed page, treat it as a general corroborating data point, not the number to build your math on. Use the ASPCA/AVMA durations above instead.
Water Math, Per Animal
Dogs have a vet-reviewed formula. PetMD, reviewed by Jennifer Larsen, DVM, PhD, DACVN, puts daily water need at approximately 1 ounce per pound of body weight per day, explicitly framed as a general estimate that varies by individual dog: not a fixed rule, and never a reason to restrict water without your vet’s direction.
| Dog’s weight |
Daily water (1 oz/lb) |
7-day supply |
| 10 lb |
10 oz (0.08 gal) |
70 oz (0.55 gal) |
| 25 lb |
25 oz (0.2 gal) |
175 oz (1.4 gal) |
| 50 lb |
50 oz (0.4 gal) |
350 oz (2.7 gal) |
| 90 lb |
90 oz (0.7 gal) |
630 oz (4.9 gal) |
Cats don’t have an equivalent vet-sourced formula. We looked for an AVMA-, ASPCA-, or vet-school-published ounce-per-pound figure for cats and didn’t find one, only pet-industry blog aggregations, which we’re not presenting as veterinary fact. For a cat, size water by the ASPCA/AVMA 7-day duration guidance rather than a per-pound calculation: pack enough bottled water to refill a cat’s bowl daily for the full duration, and lean on your vet for anything more precise about your specific cat.
Multi-animal households: add, don’t average. A 10 lb cat and a 90 lb dog don’t “average out” to a medium water need. Calculate each animal separately, then sum. This is the single most common go-bag math mistake: eyeballing a household total instead of adding real per-animal numbers.
Food Math, Per Animal
Food math is messier than water math because calorie density varies by product. PetMD’s own vet-authored dog feeding chart (Jennifer Coates, DVM) is tied to one specific food’s calorie density and explicitly instructs readers to use their own bag’s feeding chart instead of a universal number. A dog’s actual needs can run 50% above or below “typical” depending on the individual and the food.
The rule that actually works: read your own bag. Every commercial pet food package prints a feeding chart in cups or ounces per day, scaled to your pet’s weight. Multiply that daily amount by your target duration (7 days, per the ASPCA/AVMA overlap above), and that’s your per-animal food number, not a number from this page or any other general guide.
As a rough planning range so you know what to expect before you check your own bag:
| Animal |
Typical daily dry food |
7-day supply |
| Cat (8-12 lb) |
0.25-0.5 cup (~1 oz per lb of body weight caloric range, food-dependent) |
~1.75-3.5 cups (roughly 0.75-1.5 lb) |
| Small dog (10-25 lb) |
0.75-1.5 cups |
~5-10.5 cups (roughly 2.5-5.5 lb) |
| Medium dog (25-50 lb) |
1.5-2.5 cups |
~10.5-17.5 cups (roughly 5.5-9 lb) |
| Large dog (50-90 lb) |
2.5-4 cups |
~17.5-28 cups (roughly 9-14.5 lb) |
These ranges are planning anchors, not a substitute for your actual food’s printed chart. Cup-to-weight conversion depends on that food’s specific density, so confirm against the bag before you buy a container sized to hold it.
Medication Math
This one is the least ambiguous number on the page: both ASPCA and AVMA independently converge on a 2-week supply of any medication your pet needs, kept in a waterproof container. Two independent authorities landing on the identical figure is about as solid as sourcing gets in this space.
Per animal on medication, that means:
- 14 days of dosing, in whatever form the prescription takes (pills, liquid, injectable)
- A waterproof container: a zip-top bag inside a hard case, or a dedicated pill organizer
- A label identifying which pet each medication belongs to, critical the moment you’re managing more than one animal’s meds under stress
Neither authority publishes a rotation interval for the medication itself beyond general kit maintenance. Build a medication check into whatever rotation schedule you already use for food and water (see emergency food and water storage for the 6-month CDC water-rotation cadence most households anchor to).
Litter Math for Multi-Cat Households
Litter isn’t covered by ASPCA or AVMA duration guidance, so this section draws on pet-industry sources instead of veterinary authorities, flagged clearly, because that’s a different tier of source.
Boxes: Cats.com’s widely repeated rule of thumb is one litter box per cat, plus one extra, so 2 cats need 3 boxes minimum, sized at roughly 1.5 times the length of your largest cat. This is a pet-publisher guideline, not a clinical standard, but it’s a reasonable planning default in the absence of anything more authoritative.
Volume: neither ASPCA nor AVMA publishes a litter-volume figure, and the litter-industry source we checked (Litter-Robot) doesn’t publish a clean per-cat, per-day weight either. It only says a multi-cat household’s traditional boxes typically need full servicing about once a week. Rather than manufacture a number that isn’t published, treat litter as a “pack what keeps your boxes usable for the duration” item: bring enough fresh litter to service 2-3 boxes for 7 days, plus a scoop and sealable disposal bags, and size it against your own boxes’ capacity rather than a per-pound formula that doesn’t exist yet.
Scoop at least once daily under normal conditions; Cats.com specifically recommends twice daily in multi-cat homes, which is worth planning for if your evacuation kit needs to function for several days in a shelter or vehicle.
Worked Example: 2 Cats (10 lb each) + 1 Dog (50 lb), 7 Days
Here’s the full multiplication, using the ASPCA/AVMA 7-day overlap target:
Water:
| Animal |
Daily (formula) |
7-day total |
| Cat #1 (10 lb) |
Duration-based, not per-lb (no vet formula for cats) |
~7-day bottled reserve, refilled daily from stored supply |
| Cat #2 (10 lb) |
Same as above |
Same as above |
| Dog (50 lb) |
50 oz (1 oz/lb formula) |
350 oz = 2.7 gallons |
Because cats lack a per-pound formula, size each cat’s 7-day water the same practical way you’d size a 7-day human supply for a small household member: enough bottled water to refill a bowl daily. As a working estimate consistent with the dog formula’s scale (applying the same 1 oz/lb/day rate, though this is not vet-confirmed for cats), a 10 lb cat works out to about 70 oz (0.55 gallons) over 7 days, so two 10 lb cats add up to roughly 1.1 gallons combined for 7 days. Total household water: roughly 2.7 gallons (dog) + ~1.1 gallons (2 cats) ≈ 3.8 gallons, before adding a safety margin for heat or stress. Round up to the WaterBrick’s 3.5-gallon-per-brick sizing above, meaning this household needs at least two bricks for water alone.
Food (using the planning ranges above, confirmed against actual bag labels before buying containers):
| Animal |
7-day dry food estimate |
| Cat #1 (10 lb) |
~1-1.5 lb |
| Cat #2 (10 lb) |
~1-1.5 lb |
| Dog (50 lb) |
~5.5-9 lb |
Household food total: roughly 7.5-12 lb for 7 days, well within a single Gamma2 Vittles Vault’s capacity, with room for the household’s rotation buffer.
Litter (2 cats): 3 litter boxes minimum, plus enough fresh litter to service those boxes for 7 days. No published spec exists for exact volume, so size it against your own boxes rather than a fixed weight target.
Medication (if applicable): 14 days per medicated animal, in a waterproof, per-pet-labeled container. Two EZY DOSE weekly cases per medicated pet covers the full ASPCA/AVMA 2-week rule.
Household 7-day total, before containers and bag weight: approximately 3.8 gallons of water (~32 lb) + 7.5-12 lb of food + litter supplies (sized to your own boxes, no fixed weight target) + medication organizers. Water is the heaviest single line item by a wide margin, so plan your container and carry strategy around that fact.
The Weight-of-Bag Reality Check
Every duration number above assumes you can actually carry what you calculate. None of the named authorities (not FEMA, not Ready.gov, not ASPCA, not AVMA) publish a standard for how much a go-bag should weigh relative to the person carrying it. That’s a genuine gap in the official guidance, and it matters: a mathematically “correct” 7-day, multi-pet supply can easily weigh more than one adult can carry alongside two cat carriers and a leashed dog.
A commonly repeated figure in general prepping and backpacking circles, not from a government or veterinary source, and labeled here as general guidance rather than an official standard, suggests a carried bag run about 10-20% of the carrier’s body weight, scaled to fitness level. For a 150 lb adult, that’s roughly 15-30 lb of carryable gear, which is far short of the roughly 32 lb of water alone in the worked example above.
What that mismatch means in practice:
- A full multi-day, multi-pet water supply is a stage-and-drive reserve, not a walk-out-the-door go-bag load. Keep the bulk (WaterBrick bricks, the Vittles Vault) staged near your vehicle or in your car, and carry only a portable, refillable amount (like the WePet 12 oz bottle) in a bag you might actually walk with.
- If you may need to evacuate on foot or with limited vehicle space, plan your carry capacity first, then work backward to how many days of supply actually fits, rather than calculating an ideal duration and assuming you’ll find a way to carry it.
- Multi-pet households should split the carry load across every adult available, and confirm ahead of time who carries which animal’s carrier versus which supply container, so it isn’t decided for the first time during an actual evacuation.
Weigh your own packed bag on a bathroom scale before you assume it’s carryable. The math above tells you what’s needed; only your own scale tells you what’s actually movable.
Vet-Wins Reminder
The numbers on this page are general planning estimates, not an individual prescription for your pet. Your veterinarian and the feeding chart on your pet’s specific food bag both take precedence over any general figure here, especially for medication dosing, which this page deliberately does not cover beyond the 2-week supply-duration rule.
If your pet shows signs of heat stress during evacuation (the AVMA lists anxiousness, excessive panting, restlessness, excessive drooling, unsteadiness, abnormal gum and tongue color, or collapse), treat it as urgent. The AVMA’s list of animal emergencies requiring immediate veterinary care separately names heat stress and heatstroke among the conditions that warrant an immediate vet visit. Move the animal to shade or a cool area, begin cooling with room-temperature wet towels, and get to the nearest vet hospital immediately; don’t wait to see if it resolves on its own.
For suspected poisoning, the ASPCA Animal Poison Control Center is available 24 hours a day, 365 days a year at (888) 426-4435 (a consultation fee may apply). Pet Poison Helpline is a second 24/7 option at 855-764-7661, which states a budget-tier per-incident consultation fee on its own site.
How We Chose
These container and organizer picks are built entirely from manufacturer-published specifications and the live Amazon product pages listed in each spec table’s source column. We did not test any of these products ourselves, and we say so plainly. Where a live ASIN couldn’t be confirmed during this research pass, we left it blank rather than guessing. Full methodology at /review-methodology.
Once your per-animal math is done, the next step is deciding who and what moves first: which pet to evacuate first covers triage logic for households that can’t move everyone and everything in one trip, and car loading with carriers for multiple pets covers fitting the carriers, containers, and supplies calculated here into an actual vehicle. For the underlying food and water storage rules referenced throughout this page, see emergency food and water storage for pets.