72-Hour Kit Calculator for Emergency Supplies

Practical intro

Use this 72-hour kit calculator to size the basic food and water core for a short emergency kit. A 72-hour kit is not a complete preparedness plan, but it is a practical starting point for power outages, storm disruption, evacuation staging, or a temporary shelter-in-place period.

When to use this calculator

• Building a three-day household kit.
• Comparing a home kit with a go-bag or vehicle kit.
• Updating water and food quantities for a different number of people.
• Checking whether a prebuilt kit has enough calories and water for the household.

Input explanation

• People is the number of people covered.
• Water per person per day is the daily gallon assumption.
• Calories per person per day is the food energy assumption.
• Days defaults to 3 for a 72-hour kit but can be changed for longer planning.
• The result does not include medicine, documents, clothing, sanitation, lighting, radio, or local hazard items.

Formula or estimation method

Step-by-step worked example

A 4-person kit for 3 days at 1 gallon per person per day needs 12 gallons of water. At 2,000 calories per person per day, it also needs 24,000 food calories. If the kit uses 400-calorie meals or bars, 24,000 / 400 = 60 servings before snacks, special diets, and reserve.

Common mistakes

• Buying a prebuilt kit without checking calories per person.
• Forgetting water weight and whether the kit must be portable.
• Ignoring prescription medicine, glasses, documents, cash, batteries, and chargers.
• Storing food that needs cooking when fuel or safe water may not be available.
• Letting kit food, water, or batteries expire.

Planning notes and limitations

• Keep the kit where it can be reached quickly, not buried behind seasonal storage.
• For evacuation, weight and portability matter more than they do for a home pantry.
• Add local hazard items such as masks, winter gear, heat supplies, or rain protection.
• Use official emergency guidance to complete the kit beyond food and water.

Emergency storage checklist

Before treating the result as a final shopping list, compare it with official local guidance, household medical and dietary needs, storage conditions, expiration dates, safe preparation methods, and the supplies needed to use the stored item safely. Emergency supplies work best when they are labeled, rotated, accessible, and practiced before a real outage or warning.

Keep a simple inventory sheet with quantity, location, purchase date, expiration or rotation date, preparation needs, and the person responsible for checking it. Review the list after storms, moves, household changes, medication changes, new pets, or any event where supplies were used. This turns the calculator result into a maintained plan instead of a one-time shopping trip.

Before you rely on the estimate

Use the calculator result as a planning baseline, then add reserve for delays, guests, pets, heat, cold, access limits, and local hazards. A stronger preparedness plan combines quantity math with safe storage, realistic use, official alerts, evacuation decisions, and regular review.