Start with this decision
Start with people and days, then work into water, food, power, fuel, and cold-storage timing.
Emergency Preparedness Calculators
Prepare without guessing. These calculators help estimate emergency water, food, generator runtime, backup power, battery storage, and basic storm supplies.
Updated May 2026No signup requiredBuilt for mobile
Start Here
Top storm prep calculators by intent
Use this hub to plan supplies, water, power, food, freezer timing, and household readiness before the forecast gets urgent.
Common next step
Pair storm supply estimates with generator runtime and water storage so essentials are covered first.
Round in the useful direction
Round up for pets, medical needs, rural access, heat, and longer-than-expected outages.
Start Here
Start with water, then power
Water is usually the first baseline. After that, check food, power, generator runtime, and battery backup needs.
Emergency planning note
Use at least 1 gallon of water per person per day as a baseline, and store extra for heat, pets, illness, cooking, and sanitation. Generator and fuel decisions should follow manufacturer instructions and local safety guidance.
Tools
Water and food
Plan household water and emergency food reserves.
Tools
Power and outage planning
Estimate generator, battery, and backup power needs.
Tools
Storm and evacuation
Plan storm supplies, debris, and evacuation loads.
Emergency planning checklist
- Estimate water for each person and day.
- Add extra water for pets, heat, cooking, and sanitation.
- Estimate food calories and special diet needs.
- Plan generator fuel and battery backup before an outage.
- Keep printed or saved plans available when internet service is down.
FAQ
Common questions
How much emergency water should I store?
A common baseline is at least 1 gallon per person per day, plus extra for heat, pets, illness, cooking, and sanitation.
Which emergency calculator should I use first?
Start with water, then food, then power and fuel needs.
Should I plan for more than three days?
Many households choose 7 to 14 days or more depending on location, storm risk, rural access, and medical needs.
Can generator runtime estimates be exact?
No. Runtime changes with load, fuel, maintenance, generator size, and conditions.
Do these tools replace official emergency guidance?
No. Use them as planning estimates alongside local emergency management guidance and manufacturer instructions.
Topic cluster
Backup power and outage planning
Use these related tools together for better planning instead of treating each estimate as a one-off number.
New and related
Kits, bags, and emergency supplies
These tools strengthen the topic cluster and send visitors to the most useful next calculator.
Backup planning
Generators, propane, batteries, solar, food, water, and emergency cash calculators
Use these calculators to plan generator cost, maintenance, dual fuel choices, refrigerator runtime, CPAP backup, portable power stations, solar recharge, emergency food, filter capacity, and cash reserves.
Generator Fuel Cost Per Hour CalculatorEstimate generator operating cost per hour, per day, and per outage.Generator Oil Change Interval CalculatorEstimate when generator oil changes are needed during extended runtime.Dual Fuel Generator Cost CalculatorCompare gasoline and propane generator runtime and cost.Refrigerator Outage Runtime CalculatorEstimate how long a battery, power station, or generator can support a refrigerator or freezer.CPAP Battery Backup CalculatorEstimate battery size and runtime for CPAP backup power.Portable Power Station Size CalculatorEstimate power station capacity needed for devices during outages, camping, or RV use.Solar Recharge Time CalculatorEstimate how long solar panels take to recharge a battery or power station.Emergency Food Storage CalculatorEstimate emergency food days, meals, servings, and calories by household size.Water Filter Capacity CalculatorEstimate water filter capacity needed for a household during an emergency.Emergency Cash CalculatorEstimate emergency cash needs for fuel, food, lodging, supplies, and evacuation.
How to use this estimate
The emergency preparedness hub helps turn a vague supply list into measured water, food, power, battery, and storm-planning numbers. It is useful before hurricane season, winter storms, wildfire evacuations, extended outages, and rural access interruptions where stores or fuel stations may be unavailable.
Inputs that matter most
- Household size, pets, days of independence, climate, medical needs, and sanitation needs.
- Essential loads, generator fuel, battery capacity, food calories, and water reserve.
- Local hazard type, likely outage length, evacuation distance, and storage space.
- Official local emergency guidance and equipment manuals for final safety decisions.
Formula and method
Emergency planning works best in layers. Estimate the household baseline first, then add reserves for heat, pets, illness, cooking, hygiene, charging, and delayed resupply. For power, calculate essential loads before estimating fuel or battery duration.
The best result is not always the biggest number. A realistic plan balances water, food, light, communications, medications, heat, cooling, safe cooking, and the ability to rotate supplies before they expire.
Worked example
Example: a family of four planning for seven days can start with emergency water storage. At one gallon per person per day, the baseline is 28 gallons before pets, heat, cooking, or sanitation. If the same family wants refrigeration and device charging, the generator runtime and battery calculators help estimate fuel and backup energy for the loads that matter most.
Common planning mistakes
- Planning food without enough stored water for cooking, cleaning, and pets.
- Counting generator power without storing safe fuel or reading the manual.
- Forgetting that medical equipment, infants, elderly relatives, and extreme heat can change the baseline.
- Keeping every plan online when internet service may be unavailable.
Safety and disclaimer note
These emergency calculators support household planning and are not professional emergency, medical, electrical, or safety advice. Follow local emergency management instructions, public health guidance, manufacturer specs, and qualified professional advice for generators, fuel, electrical work, medical needs, and evacuation decisions.
FAQ
Practical questions
How many days should I plan for?
Many households start with three days, then expand to seven or fourteen days depending on local risk, rural access, storm history, and medical needs.
Should water or power come first?
Water usually comes first because it affects drinking, cooking, sanitation, pets, and hygiene. Power planning comes next for refrigeration, communication, and medical needs.
Can I rely on a generator for everything?
Usually no. Generators require fuel, maintenance, outdoor operation, and safe connections. Plan non-electric backups for critical needs too.
Do emergency calculators replace official guidance?
No. Use them as estimating aids alongside local emergency management and public health guidance.
How often should I update my plan?
Review it before high-risk seasons, after equipment changes, when household size changes, and when stored food, water, or fuel is rotated.
More tools
Fuel, light, solar, and RV backup tools
Use these calculators when outage planning includes stored fuel, lanterns, portable solar, RV loads, or backup runtime.
Fuel Rotation CalculatorPlan fuel rotation before stored fuel ages out.Fuel Stabilizer Mix CalculatorEstimate stabilizer mix for stored fuel.Lantern Runtime CalculatorEstimate light runtime during outages or trips.Portable Solar Charging CalculatorEstimate charging time for portable solar setups.RV Power Consumption CalculatorEstimate RV loads before sizing backup power.Solar Backup Runtime CalculatorEstimate backup runtime from solar and batteries.RV Solar CalculatorEstimate RV solar needs for backup and travel.Tractor Fuel Usage CalculatorPlan fuel for cleanup, chores, or rural outages.Trail Camera Battery Runtime CalculatorEstimate remote battery runtime.Food Storage Duration CalculatorEstimate how long stored food may last for a household.