Emergency Kit Calculator
Calculate 72-hour emergency kit supplies for your household — water, food, batteries, first aid, and more.
About this calculator
Built around FEMA and Ready.gov's 72-hour kit guidance — which recommends storing one gallon of water per person per day for several days, covering both drinking and basic sanitation — this calculator scales every core supply category to your household's actual composition rather than giving one generic number. Water is the biggest line item: it allots that full FEMA-standard gallon per adult per day, 0.75 gallons for each child, 0.5 gallons for infants, and 0.25 gallons per pet, all multiplied by your target kit duration. Food is derived from daily caloric need — 2,000 calories for adults, 1,500 for children, 500 for infants — then converted into practical units: emergency food bars at roughly 250 calories each, or MREs at about 1,250 calories each, so you can decide which format fits your storage space and budget. Infants get a separate formula allowance of 26 ounces per day, and pets get one pound of pet food per day, both independent of the calorie math since neither eats standard rations.
Batteries are estimated at two AAA per person per day for flashlights and radios, and first aid kits scale up by one extra kit for every additional week of planned duration. If you flag prescription medication needs, the calculator adds your kit duration plus a two-day buffer to ensure you don't run out right as help arrives. Estimated weight leans heavily on water, which is genuinely the heaviest component at 8.34 lb per gallon — a detail worth remembering when deciding how much to store versus how you'll transport it if you need to evacuate rather than shelter in place.
Inputs
Results
Water needed (gal)
8.3
Figures current as of 2026. Source: Ready.gov (FEMA), "Build A Kit"
How to Use This Calculator
- Enter the number of Adults, Children (1-12), Infants (under 1 yr), and Pets in the household.
- Set Kit Duration (days) — FEMA recommends a minimum of 72 hours, ideally 2 weeks.
- Toggle Prescription Medications if household members have ongoing medical needs.
- Review Water Needed (gallons) — 1 gallon per person per day is the baseline.
- Use the full supply list to stock food, first aid, documents, and sanitation items.
What each input means
- Adults
- Number of adults (age 13+) in the household.
- Children (1-12 yrs)
- Number of children aged 1-12.
- Infants (< 1 yr)
- Number of infants requiring formula.
- Pets
- Number of dogs/cats (adjusts water and food).
- Kit duration (days)
- Target duration — FEMA recommends minimum 3 days, ideally 7-14.
- Prescription medications (0/1)
- Set to 1 if any household member requires daily prescription medications.
What each result means
- Water needed (gal)
- Total gallons of water to store for the kit duration.
- Total calories needed
- Total caloric requirement for all people for the full duration.
- MREs needed
- Meals Ready-to-Eat (1,250 cal each) — or equivalent packaged meals.
- Emergency food bars
- 250-calorie emergency food bars as an alternative to MREs.
- Infant formula (oz)
- Ounces of infant formula needed (26 oz/day per infant).
- Pet food (lbs)
- Pounds of pet food needed (~1 lb/pet/day).
- Batteries (AAA)
- Batteries for flashlights and emergency radio.
- First aid kits
- First aid kit(s) recommended.
- Medication supply (days)
- Days of prescription medication to include (with 2-day buffer).
- Est. kit weight (lbs)
- Approximate total weight of the emergency kit.
- Est. kit cost ($)
- Rough cost estimate for purchasing all kit supplies.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersAdults = 2, Children (1-12 yrs) = 1, Infants (< 1 yr) = 0, Pets = 0 = 6 input(s) provided
- Calculate Water neededWater needed = (adults * 1 + children * 0.75 + infants * 0.5 + pets * 0.25) * durationDays8.3 = 8.3
- Calculate Total calories neededTotal calories needed16500 = 16500
- Calculate MREs neededMREs needed14 = 14
Figures and sources
- 72-hour emergency kit water guidance (1 gallon per person per day) (2026) — Ready.gov (FEMA), "Build A Kit"
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
What does Estimated Cost include, and why might I spend less than it says?
It prices the consumables the calculator actually sizes — roughly $2 per gallon of water capacity and $8 per MRE — plus small allowances for infant, pet and medication supplies and a flat $50 for miscellaneous gear. That $50 is a placeholder, not a priced list, and nothing here accounts for the durable items you buy once and keep: flashlights, a hand-crank radio, a stove, containers. A household restocking an existing kit usually comes in well under the figure; one building from nothing should expect to spend more.
Why do children get 0.75 gallons of water per day instead of the full gallon adults get?
The calculator scales water allocation to body size and typical consumption needs: adults get the full FEMA-standard 1 gallon per day (drinking plus sanitation), children get 0.75 gallons, and infants get 0.5 gallons, reflecting that smaller bodies generally need less water for the same drinking-plus-hygiene coverage. Pets get a separate 0.25 gallons per day, added on top of the household total.
Should I choose MREs or emergency food bars for my kit?
The calculator converts your household's total caloric need into both units so you can compare: MREs are assumed at about 1,250 calories each, meaning fewer items to store and prepare, while food bars are assumed at about 250 calories each, meaning more individual units but often lighter weight and no cooking required. Since totalCalories drives both figures identically, the choice comes down to storage space, budget (MREs are pricier per unit in the cost estimate), and whether you want fewer bulky meals or more compact bars.
Why does my first aid kit count only increase every 7 days of duration?
The formula is 1 base kit plus one additional kit for every full 7-day period in your target duration (Math.floor(durationDays / 7)), so a 3-day or 6-day kit both show just 1 kit, while a 10-day kit shows 2. This models the assumption that a standard first aid kit's contents cover roughly a week of typical usage before needing replenishment or a spare kept in reserve.
What does the medication buffer actually account for?
When you flag prescription medication needs, the calculator adds your full kit duration plus 2 extra days (medicationDays = durationDays + 2) rather than just matching the duration exactly. That 2-day buffer exists so a delay in reaching a pharmacy or in help arriving doesn't leave someone without medication right at the moment supplies would otherwise run out.
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