Sources

Each number in the calculator and the outage planner comes from one of the sources below. Where a source gives a direction without an amount, the planning choice is written out so you can judge it.

Rules the tools use

Rule	Value	Source
Stored water, drinking plus hygiene	1 gallon per person per day	Ready.gov (FEMA); Centers for Disease Control and Prevention; FEMA and the American Red Cross
Drinking share of that gallon (two quarts)	0.5 gallon per person per day	FEMA and the American Red Cross
Hot weather: drinking needs can double	2 times the drinking share	Ready.gov (FEMA); FEMA and the American Red Cross
Nursing or medical needs: one more drinking share per day Ready.gov, the CDC, and the Red Cross say nursing mothers and sick people may need more water but give no amount. The calculator adds one more drinking share per day (a half gallon, or a gallon in hot weather), which is the same doubling Ready.gov gives for heat.	1 extra daily drinking share for the household	Ready.gov (FEMA); Centers for Disease Control and Prevention; FEMA and the American Red Cross
Adults (19 and up)	2,000 calories per day	U.S. Food and Drug Administration; USDA and HHS
Teens (14 to 18): a moderately active 16-year-old, boy 2,800 and girl 2,000, averaged	2,400 calories per day	USDA and HHS
Children 9 to 13: a moderately active 11-year-old, boy 2,000 and girl 1,800, averaged	1,900 calories per day	USDA and HHS
Children 4 to 8: a moderately active 6-year-old, boy 1,600 and girl 1,400, averaged	1,500 calories per day	USDA and HHS
Toddlers 1 to 3: a moderately active 2-year-old, boy and girl both 1,000	1,000 calories per day	USDA and HHS
Dog drinking water	1 fluid ounce per pound per day	Hill's Pet Nutrition (veterinarian reviewed)
Cat drinking water	4 fluid ounces per 5 pounds per day	Cornell Feline Health Center
Replace water you filled yourself	6 months	Ready.gov (FEMA); Centers for Disease Control and Prevention; FEMA and the American Red Cross
Treating water by boiling	1 minute at a rolling boil	Ready.gov (FEMA)
Above this elevation, boil water longer	6,500 feet of elevation	Centers for Disease Control and Prevention
Boiling water at high elevation	3 minutes at a rolling boil	Centers for Disease Control and Prevention
Sanitizing a container before you fill it with water	1 teaspoon of unscented bleach per quart of water	Centers for Disease Control and Prevention; Ready.gov (FEMA)
Where to keep stored water, out of direct sunlight	50 to 70 degrees F	Centers for Disease Control and Prevention
Freezer temperature to check with an appliance thermometer	0 degrees F or below	Centers for Disease Control and Prevention
Soaking hand-washed dishes during a boil water advisory, at least 1 minute	1 teaspoon of unscented bleach per gallon of warm water	Centers for Disease Control and Prevention
A dishwasher this hot, or with a sanitizing cycle, is generally safe during a boil water advisory	150 degrees F final rinse	Centers for Disease Control and Prevention
Treating water with bleach	1/8 teaspoon of unscented household bleach per gallon	Ready.gov (FEMA)
Bleach strength to use for treating water	5.25 to 6.0 percent sodium hypochlorite	Ready.gov (FEMA)
Wait before using bleach-treated water	30 minutes after stirring	Ready.gov (FEMA)
An unopened refrigerator keeps food cold	4 hours	Ready.gov (FEMA); Centers for Disease Control and Prevention
A full freezer with the door closed keeps food safe	48 hours	Centers for Disease Control and Prevention
A half-full freezer with the door closed keeps food safe	24 hours	Centers for Disease Control and Prevention
Food temperature line: safe at or below, thrown out after 2 hours at or above	40 degrees F	Centers for Disease Control and Prevention; Ready.gov (FEMA)
Throw out food held that warm for this long or longer	2 hours	Ready.gov (FEMA)
A generator runs outside, farther than this from windows, doors, and vents	20 feet	Centers for Disease Control and Prevention
Keep a portable heater this far from things that burn	3 feet	U.S. Consumer Product Safety Commission
Refrigerator energy use An ENERGY STAR 18.1 cubic foot top-freezer model. Refrigerators cycle on and off, so the planner spreads the yearly figure over every hour: about 41.5 watts around the clock. Larger, older, or side-by-side models use more.	363.5 kWh per year	U.S. Department of Energy (FEMP); U.S. Department of Energy
Separate freezer energy use ENERGY STAR gives about 215 kWh a year for a chest freezer and about 395 for an upright. The planner uses the higher upright figure, spread over every hour.	395 kWh per year	ENERGY STAR (U.S. EPA and DOE); U.S. Department of Energy
CPAP without a humidifier The maker lists 0.93 amps at 12 volts for one common model at a pressure of 10 cm H2O, about 11 watts. Higher pressures and other models draw more. The device label or maker gives the real number.	11 watts	ResMed (device maker); U.S. Department of Energy
CPAP with a heated humidifier The same model at 10 cm H2O with the humidifier at setting 8 draws 3.66 amps at 12 volts, about 44 watts. Heated tubing adds more. The device label or maker gives the real number.	44 watts	ResMed (device maker); U.S. Department of Energy
CPAP use per night The maker sizes its battery tables for 8 hours a night. Use your own hours if they differ.	8 hours a night	ResMed (device maker)
Home oxygen concentrator The average power use the maker lists for one common stationary model. Other models differ, and the device label or maker gives the real number.	350 watts	Philips Respironics (device maker)
Oxygen concentrator use per day The planner assumes the concentrator runs all day. Fewer hours of use means fewer watt-hours.	24 hours a day	Philips Respironics (device maker)
Power wheelchair or scooter charger One maker lists a charger putting out 8 amps at 28.8 volts at 85% efficiency or better, about 271 watts from the wall while charging hard. Smaller chargers draw less.	271 watts	Pride Mobility (device maker); U.S. Department of Energy
Charging time per day The site’s planning choice. Chargers slow down as the batteries fill, so 4 hours at full draw stands in for a longer, tapering charge. Check how long yours takes.	4 hours a day	Pride Mobility (device maker)
Power station efficiency: the share of its rated capacity you can use No government source gives a figure for portable power stations. A Department of Energy lab uses 85% round-trip efficiency for home battery systems, so the site starts there. Change it on the form to match your station’s manual.	85 percent of rated watt-hours	National Laboratory of the Rockies (U.S. Department of Energy)
Electric space heater The figure NREL uses for a personal space heater. The label on yours gives the real number.	1,500 watts	National Renewable Energy Laboratory; U.S. Department of Energy
Space heater use per day The site’s planning choice. Use your own hours.	8 hours a day	U.S. Department of Energy
Window air conditioner An ENERGY STAR 12,000 Btu/h room unit uses 612 kWh over 750 hours of use, about 816 watts while it runs. Other sizes differ, and the label gives the real number.	816 watts	U.S. Department of Energy (FEMP); U.S. Department of Energy
Window air conditioner use per day The site’s planning choice. Use your own hours.	8 hours a day	U.S. Department of Energy
TV An ENERGY STAR 54.5-inch LED TV uses 168 kWh a year over 1,825 viewing hours. Counting all of it as viewing time gives about 92 watts, a little high. Smaller screens use less.	92 watts	U.S. Department of Energy (FEMP)
TV use per day The 1,825 viewing hours a year the Department of Energy figures on, spread over every day.	5 hours a day	U.S. Department of Energy (FEMP)
LED bulb, as bright as an old 60-watt bulb	9 watts per bulb	Federal Trade Commission
Lights on per day The site’s planning choice. Use your own hours.	5 hours a day	U.S. Department of Energy
Phone charger energy use Spread over every hour, about 0.4 watts, or about 10 Wh a day per phone.	3.5 kWh per year	National Renewable Energy Laboratory (for the U.S. Department of Energy)
Modem or Wi-Fi router energy use NREL’s figure for a cable or DSL modem, left on all day: about 6 watts.	52.6 kWh per year	National Renewable Energy Laboratory (for the U.S. Department of Energy)

Pet sizes (small dogs about 20 lb, medium about 50 lb, large about 90 lb, cats about 10 lb), the 24-bottle case of 16.9-ounce bottles, and the starting value of 200 calories per serving are the site’s own round numbers for the shopping list. Change the serving size to match your labels.

Source documents

Water, Ready.gov (FEMA). Checked 2026-11-11.
At least one gallon per person per day for drinking and sanitation; more for children, nursing mothers, sick people, and hot weather, where needs can double; replace water that was not commercially bottled every six months; how to treat water with boiling or bleach.
How to Create an Emergency Water Supply, Centers for Disease Control and Prevention. Checked 2026-11-12.
At least one gallon per person per day for 3 days, a 2-week supply if possible, more for pregnant women, sick people, pets, and hot climates; replace home-filled water every six months; keep unscented bleach with 5% to 9% sodium hypochlorite; use food-grade containers with tight tops, never ones that held toxic chemicals; sanitize a container with 1 teaspoon of unscented bleach in 1 quart of water, shake, wait at least 30 seconds, and pour it out; store containers at 50°F to 70°F away from sunlight and away from gasoline and pesticides.
Food and Water in an Emergency, FEMA and the American Red Cross. Checked 2026-11-11.
A normally active person drinks at least two quarts (half a gallon) a day; store at least one gallon per person per day to cover food preparation and hygiene too; aim for a two-week supply; never ration water; shelf-life groups for common pantry foods; first in, first out.
Food, Ready.gov (FEMA). Checked 2026-11-11.
Store at least a several-day supply of non-perishable food your family will eat, including food for infants; use ready-to-feed formula, or bottled or boiled water if formula must be mixed.
Keep Food Safe After a Disaster or Emergency, Centers for Disease Control and Prevention. Checked 2026-11-11.
Keep appliance thermometers in the refrigerator (40°F or below) and freezer (0°F or below); with the doors closed, food stays safe up to 4 hours in a refrigerator, 48 hours in a full freezer, and 24 hours in a half-full freezer; after 4 hours, move perishable food to a cooler with ice; never taste food to judge it; thawed food that still has ice crystals or is at 40°F or below can be refrozen or cooked; throw out food that touched floodwater, and bulging or damaged cans.
Safety Skills: Know How to Shut Off Utilities, Ready.gov (FEMA). Checked 2026-11-11.
Everyone in the household should know where the gas shutoff, the main water valve, and the electrical circuit box are; if you turn off the gas for any reason, only a qualified professional can turn it back on.
Dietary Guidelines for Americans, 2020-2025, Appendix 2 (Table A2-2), USDA and HHS. Checked 2026-11-11.
Estimated daily calorie needs by age, sex, and activity. Moderately active, boy and girl: 1,000 and 1,000 at age 2; 1,600 and 1,400 at age 6; 2,000 and 1,800 at age 11; 2,800 and 2,000 at age 16. Adults range from 1,600 to 3,000 depending on sex, age, and activity.
How to Understand and Use the Nutrition Facts Label, U.S. Food and Drug Administration. Checked 2026-11-11.
2,000 calories a day is the general guide for nutrition advice; calories on the label are per serving, and the label lists servings per container.
Prepare Your Pets for Disasters, Ready.gov (FEMA). Checked 2026-11-11.
Keep several days of pet food in an airtight, waterproof container and several days of water, plus extra medicine your pet takes.
How Much Water Should Dogs & Cats Drink Each Day?, Hill's Pet Nutrition (veterinarian reviewed). Checked 2026-11-11.
A general rule for dogs is about 1 fluid ounce of water per pound of body weight per day; active dogs and dogs in hot climates drink more.
Hydration, Cornell Feline Health Center. Checked 2026-11-11.
Cats need about 4 ounces of water per 5 pounds of lean body weight per day, so a 10-pound cat needs about a cup.
Carbon Monoxide (CO) Poisoning Basics, Centers for Disease Control and Prevention. Checked 2026-11-11.
Never use a generator inside your home or garage, even if doors and windows are open; only use generators outside, more than 20 feet from windows, doors, and vents; use a battery-powered or battery backup CO detector when using a generator; never heat your house with a gas oven.
Power Outages, Ready.gov (FEMA). Checked 2026-11-11.
Keep freezers and refrigerators closed; have flashlights for every household member; plan for a portable charger or power bank; disconnect appliances and electronics to avoid damage from surges; do not use a gas stove or oven to heat your home; have alternate plans for refrigerating medicines and power-dependent medical devices, and find out how long medication can be stored at higher temperatures; go to a community location with power if heat or cold is extreme; throw away food exposed to 40 degrees or higher for two hours or more.
Estimating Appliance and Home Electronic Energy Use, U.S. Department of Energy. Checked 2026-11-11.
Wattage times hours used per day gives daily energy use; the wattage on the label is the maximum draw; refrigerators cycle on and off, so they run at full wattage only part of the time.
Purchasing Energy-Efficient Residential Refrigerators, U.S. Department of Energy (FEMP). Checked 2026-11-11.
An ENERGY STAR 18.1 cubic foot top-freezer refrigerator with automatic defrost uses 363.5 kWh a year.
Freezers, ENERGY STAR (U.S. EPA and DOE). Checked 2026-11-11.
An ENERGY STAR certified chest freezer uses about 215 kWh a year and an upright freezer about 395 kWh a year.
Battery Guide, ResMed (device maker). Checked 2026-11-11.
Current draw at 12 volts DC for an AirSense 10 at each pressure, with and without the humidifier, and battery sizes for 8 hours of use. At 10 cm H2O: 0.93 amps without a humidifier and 3.66 amps with the humidifier at setting 8.
EverFlo Oxygen Concentrator Specifications, Philips Respironics (device maker). Checked 2026-11-11.
A stationary home oxygen concentrator, 120 volts, average power consumption 350 watts.
Battery Charger Instructions, Pride Mobility (device maker). Checked 2026-11-11.
An off-board charger for 24-volt power chair and scooter batteries: 8 amps output at 28.8 volts, at least 85% efficient, 3.8 amps maximum input.
Keep Warm and Safe This Winter: Tips for Using Generators, Furnaces and Space Heaters, U.S. Consumer Product Safety Commission. Checked 2026-11-11.
Keep portable heaters at least three feet from drapes, furniture, bedding, and other things that burn; plug electric space heaters directly into a wall outlet, never into an extension cord or power strip; turn heaters off when sleeping; never refuel a fuel-burning heater or a generator while it runs, and let it cool first; CO alarms on every level with battery backup; use battery-powered flashlights or lanterns instead of candles.
FDA Offers Tips about Medical Devices and Natural Disasters, U.S. Food and Drug Administration. Checked 2026-11-11.
Read the user instructions or call the device maker to find out if a device can run on batteries or a generator; use battery-powered flashlights or lanterns rather than gas lights when oxygen is in use; check settings after the power returns.
Annual Technology Baseline: Residential Battery Storage, National Laboratory of the Rockies (U.S. Department of Energy). Checked 2026-11-11.
Round-trip efficiency is the ratio of useful energy output to useful energy input; the lab adopts 85% as a representative round-trip efficiency for a home lithium-ion battery system of 5 kW and 12.5 kWh.
The Road to Net Zero, National Renewable Energy Laboratory. Checked 2026-11-11.
In the lab’s office energy plan, removing a personal space heater saves 1,500 watts.
Purchasing Energy-Efficient Room Air Conditioners, U.S. Department of Energy (FEMP). Checked 2026-11-11.
An ENERGY STAR room air conditioner of 12,000 Btu/h uses 612 kWh a year when run 750 hours a year.
Purchasing Energy-Efficient Televisions, U.S. Department of Energy (FEMP). Checked 2026-11-11.
An ENERGY STAR 54.5-inch LED TV uses 168 kWh a year, figured on 1,825 hours a year turned on and the rest in standby; ENERGY STAR TVs meet a 1 watt standby limit.
Shopping for Light Bulbs, Federal Trade Commission. Checked 2026-11-11.
A traditional 60-watt incandescent bulb gives about 800 lumens; an LED bulb gives the same 800 lumens on about 9 watts.
Building America House Simulation Protocols, National Renewable Energy Laboratory (for the U.S. Department of Energy). Checked 2026-11-11.
Benchmark yearly energy for household plug loads, per unit: a cell phone charger 3.5 kWh and a DSL or cable modem 52.6 kWh.
Lithium-Ion Batteries: Everyday Convenience, Hidden Fire Risks, U.S. Fire Administration (FEMA). Checked 2026-11-11.
Use only original or certified replacement chargers and cables; charge devices on solid, flat surfaces, out of direct sunlight, and not unattended when possible.
Build A Kit, Ready.gov (FEMA). Checked 2026-11-12.
A basic kit: one gallon of water per person per day for several days, a several-day supply of non-perishable food, a battery-powered or hand crank radio, a flashlight, a first aid kit, extra batteries, a whistle, a wrench or pliers for the utilities, a manual can opener, local maps, and phone chargers with a backup battery; add medicines, glasses, infant and pet supplies, cash, copies of important documents in a waterproof container, and a warm blanket for each person; keep it in one or two easy-to-carry containers; keep canned food cool and dry, replace expired items, and rethink the kit every year.
Winter Weather, Ready.gov (FEMA). Checked 2026-11-12.
A winter storm can cut off heat, power, and communication for several days; gather supplies to stay home without power; insulate and weather-strip; install and test smoke and carbon monoxide alarms with battery backups; keep generators and fuel outdoors at least 20 feet from windows, doors, and attached garages; let a generator cool before refueling; never heat a home with a gas stovetop or oven; a car kit with jumper cables, sand, a flashlight, warm clothes, blankets, water, and snacks, and a full tank of gas.
Drinking Water Advisories: An Overview, Centers for Disease Control and Prevention. Checked 2026-11-12.
Boil water, do not drink, and do not use advisories; during a boil water advisory use bottled water or bring tap water to a rolling boil for 1 minute, 3 minutes above 6,500 feet, even if it was filtered; do not use refrigerator water or ice dispensers; brush teeth with boiled or bottled water; a dishwasher is generally safe with a sanitizing cycle or a final rinse of at least 150°F; soak hand-washed dishes at least 1 minute in 1 teaspoon of unscented bleach per gallon of warm water; laundry as usual; do not swallow water when bathing, and give babies and young children a sponge bath; use ready-to-use infant formula if possible; give pets bottled or boiled water that has cooled.