Hurricane Prep Supply Calculator

How to use this calculator

Enter the household first (adults, kids, elderly, pets), then choose how many days of self-sufficiency to plan for, the storm category you expect to be exposed to, and your home situation. The calculator scales water, food, fuel, cash, and medication needs by household and storm severity, and shows the typical retail cost to acquire the stockpile from scratch. Defaults match a 4-person household preparing for a Cat 3 hit with 7 days of self-sufficiency.

Why hurricane prep is different from generic disaster prep

• Extended grid outage. Hurricane outages typically last 5 to 14 days in the impact zone, versus 1 to 3 days for most other disasters. Crews cannot work during the storm, and post-storm access roads are often blocked by fallen trees and debris for days.
• Storm surge contamination. Coastal flooding contaminates municipal water supplies with bacteria, sewage, and chemicals. Boil-water orders run 3 to 21 days after major storms. Plan stored water for the full duration, not just the days the power is out.
• Cash-only economy post-storm. Credit-card and ATM networks fail for 3 to 14 days in heavily impacted areas. Gas stations and grocery stores running on generator power often go cash-only.
• Evacuation possibility. Unlike most disasters, hurricanes have 72 hours of warning that may force a mandatory evacuation. Supplies must be portable enough to fit in a vehicle, or a parallel "shelter in place" stockpile must coexist with an evacuation kit.
• Heat without AC. Hurricane season runs June through November in the Atlantic. Power outages without AC during 90+ degree days create medical emergencies for elderly and infants within 24 hours.

Tips for accurate planning

• Match days to category. 7 days for Cat 1 to 2, 10 days for Cat 3, 14 days for Cat 4 to 5. Maria left some Puerto Rico communities without grid power for 11 months; the calculator buffers for the typical, not the worst.
• Account for vulnerable household members. Kids under 5 and adults 65+ need 50 percent more water for medication regimens, hygiene, and hydration during heat.
• Pets often forgotten. A medium dog drinks 1 gallon per day plus needs 14 days of food and any prescription medications. A cat is closer to 0.25 gallons per day.
• Stockpile half indoors, half in the car. Mandatory evacuation can come 24 to 48 hours before landfall. Pre-staging supplies in the trunk lets you leave on short notice without repacking.
• Rotate quarterly. Bottled water expires (technically the bottles, not the water), canned food has best-by dates, and gasoline degrades. The April 1, July 1, and October 1 rotation schedule covers most prep cycles.

Storm category vs preparation tier

Category	Wind speed	Typical impact	Recommended prep tier
Tropical Storm	39 to 73 mph	Tree damage, brief outages, minor flooding	3 to 5 days of supplies; full vehicle tanks
Cat 1 to 2	74 to 110 mph	Roof damage, 1 to 5 day outages, road closures	7 days of supplies; 1 backup gas can
Cat 3 (Major)	111 to 129 mph	Structural damage, 5 to 10 day outages, mass evacuations	10 days; generator + 3 to 5 day fuel reserve
Cat 4	130 to 156 mph	Catastrophic damage, 10 to 21 day outages	14 days; generator + 7 day fuel; evacuate if ordered
Cat 5	157+ mph	Devastating, weeks to months of recovery	14+ days at evacuation destination; do not shelter in path

Shelter in place vs evacuate

• Evacuate when ordered. Mandatory evacuations apply to storm surge zones (Zones A and B), mobile homes, and flood-prone areas regardless of category. Ignore mandatory orders only if you have specialized hardened structures and a clear medical reason.
• Cat 1 to 2 in a sound house outside the surge zone: shelter in place is often safer than congested evacuation routes. Stockpile 7 days; secure outdoor items; have a safe room.
• Cat 3 to 5 anywhere on the projected path: evacuate inland 50+ miles ahead of the storm cone. Leave 72 hours before landfall if possible; the last 24 hours of evacuation traffic moves at walking speed.
• Cost: shelter is roughly half the cost of evacuating. Sheltering buys supplies plus generator fuel; evacuating buys fuel for the drive plus 4 to 7 nights of lodging plus food on the road. Use the calculator's compare row for actual numbers.

Common mistakes

• Buying everything the day before landfall. Stores run out 48 to 72 hours pre-storm. Bottled water, plywood, batteries, and propane are the first to go. Stockpile during hurricane season opening (June 1) and rotate.
• Underestimating water. The single biggest hurricane prep failure. 1 gallon per person per day is the floor, not the target.
• Forgetting cash. ATMs fail when the power fails. $200 to $500 in small bills sealed in a zip bag covers most post-storm needs.
• Generator without fuel. The generator burns through 1 to 3 gallons per hour. A 5,000W generator running 8 hours per day uses 5 to 10 gallons; a week of partial use needs 35 to 70 gallons of stored gasoline.
• Pets and medications unplanned. Pet food, medications, and prescription drugs run out the same day as the storm. Refill prescriptions 14 days early at the start of hurricane season.
• Documents not protected. Insurance papers, deeds, IDs, and prescriptions need a waterproof container. Photograph each and email yourself the photos so you have cloud copies.

FAQ

How many days of supplies do I need for a hurricane?

FEMA and state emergency management offices recommend 7 days of self-sufficiency for hurricane-prone regions, twice the generic 3-day FEMA baseline. Hurricane-driven outages run longer than other disasters because crews cannot work during the storm and access roads are often blocked for days. For Cat 4 to 5 storms, plan 10 to 14 days; the post-Katrina and post-Maria timelines showed widespread outages of 2 weeks or more in the worst-hit areas.

How much water do I need per person for a hurricane?

One US gallon per person per day is the FEMA baseline (3.79 liters), covering drinking, cooking, and basic hygiene. Increase to 1.5 gallons for kids under 5 (more frequent hand washing, formula prep) and elderly adults (medication regimens, hydration). Add 1 gallon per pet per day for medium dogs, scaled by size. For a Cat 4 to 5 storm, the calculator adds a 50 percent buffer because municipal water often becomes contaminated post-storm and bottled water deliveries are interrupted for 5+ days.

What food works best for hurricane prep?

Shelf-stable, no-cook items first: peanut butter, canned beans and soups, crackers, granola bars, dried fruit, jerky, instant oatmeal. Add a manual can opener. For families with young children, include familiar comfort foods (pediatric nutritional shakes, juice boxes, pouches) since stress and disruption suppress appetite. Stock 2,000 calories per adult per day, 1,500 per kid age 4 to 12, 800 per kid under 4. Mountain House and Wise Company freeze-dried meals work but require water for preparation, count them against the water budget.

How much cash should I have for a hurricane?

Plan $200 to $400 per person in small bills (1s, 5s, 10s, 20s). Post-storm ATM and credit-card networks fail for 3 to 14 days in heavily impacted areas; gas stations, grocery stores, and even pharmacies that operate on generator power often go cash-only. Hurricane Maria left some Puerto Rico communities cash-only for 6+ months. Keep half at home in a waterproof container, half in your evacuation kit if you might evacuate.

Should I shelter in place or evacuate during a hurricane?

Evacuate when ordered to. Mandatory evacuations apply to storm surge zones (Zones A and B), mobile homes, and flood-prone areas regardless of category. For Cat 1 to 2 storms in well-built homes outside surge zones, sheltering in place is often safer than congested evacuation routes. For Cat 3 to 5 in any structure, evacuate inland 50+ miles ahead of the storm. Decision criteria: storm surge zone, home construction, medical needs, and the National Hurricane Center's track confidence at 72 hours out. The calculator's shelter-vs-evacuate compare row covers the cost difference.

How much fuel should I store?

For evacuation: full tanks in all vehicles (typical sedan tank holds 12 to 16 gallons, 350 to 450 mile range) plus one 5-gallon backup can per vehicle since gas stations within 100 miles of landfall often run dry 24 to 48 hours pre-storm. For sheltering with a generator: 1 to 3 gallons per hour at 50 percent load, multiplied by the planned days of generator runtime. Run the generator-fuel-runtime-calculator for an exact number. Stored gasoline lasts 3 to 6 months sealed; rotate quarterly.