What the Japanese government recommends

Japan is a country of earthquakes, typhoons and heavy rain, and the government asks every household to keep its own supplies. These are the guidelines the calculator uses. It only multiplies them by the number of people and days.

Water and a portable gas stove are the two must-haves. For food, the government suggests a balanced one-week stock per person. All of these are minimums, so a family with special needs, or one that lives in an area with more risk, may need more.

How to use the calculator

Enter the number of people and the number of days you want to cover. Three days is the stated minimum and one week is the stated goal. The result shows the water in liters and in two-liter bottles, the number of meals, the gas canisters and the toilet uses.

If someone in your home is a baby or small child, an older person, someone who has trouble chewing or swallowing, someone with a chronic illness or someone with a food allergy, enter how many such people there are in the third box. Only their meals are counted as at least 14 days. Water and toilet amounts are the same for everyone.

Quick table by household size

This table shows the amounts for one to six people, for 3 days and for 1 week. It counts 3 meals a day and 5 toilet uses a day.

The number in brackets is the number of two-liter bottles. A case of six bottles holds 12 liters, so two people need 4 cases for a week, and four people need 7.

Why at least 3 days, and 1 week if you can

The Government of Japan online PR site explains that, in past disasters, it took more than a week for electricity, gas and water to come back in most cases. Roads can be blocked and distribution can stop, so relief supplies may not arrive and shops may have little food. That is why it asks households to keep at least 3 days of food at home, and a week if possible.

The summary of the Ministry of Agriculture, Forestry and Fisheries' food stock guide says the same, and adds that people may want to keep more, such as 2 weeks, depending on the situation in their area. Your city's hazard map shows what is most likely to happen where you live, and it is a good place to start when you decide how much to keep.

Water

Plan on about 3 liters per person per day, for drinking and cooking together. For the minimum 3 days, that is 9 liters per person. The Ministry of Agriculture, Forestry and Fisheries notes that 5 two-liter bottles give one person that minimum. Water for heating pouch meals in hot water, or for washing food and dishes, is needed on top of this.

Tap water counts as stored water, too. According to the government PR site, tap water is disinfected with chlorine and can be used for drinking for about 3 days. Fill a clean container to the brim, close it tightly and keep it somewhere cool. If you prefer to buy bottles and replace them as you use them, you can. For people who want less work, the ministry recommends water that keeps for a long time.

Food and rolling stock

The government recommends "rolling stock" (rōringu sutokku). You buy a little more of the food you already eat, eat the oldest first, and buy more to replace what you ate, so there is always a stock at home. The PR site gives three tips: buy extra of what you normally eat, eat it as part of everyday meals, and replenish what you eat.

As an example for two adults for one week, the PR site lists 18 cans of meat, vegetables or beans, 18 pouches of retort main dishes, 6 more pouches such as pasta sauce, two 2 kg bags of rice, 6 cups of instant noodles, 6 packs of cooked rice, and dried noodles. Canned fish and meat give protein and keep for a long time. Right after a disaster, meals tend to be mostly carbohydrates, so it also helps to have long-lasting vegetables, vegetable juice and canned fruit.

Gas canisters

A portable gas stove and its canisters let you boil water and warm pouch meals. The government PR site gives about 6 canisters per person per week. For two adults for a week, that is 12 canisters, a little less than one per person per day. The calculator rounds up when the number of days is short.

Toilets

When the water supply is cut, flush toilets may stop working. Waste then builds up and can cause infections, pests and bad smells, and holding back can lead people to eat and drink less, which can cause dehydration and poor nutrition. The Ministry of Economy, Trade and Industry counts 5 toilet uses per adult per day and recommends a stock for one week, which is 35 uses per person. For a family of four, that is 5 times 4 times 7, or 140 uses.

A Cabinet Office magazine from 2024 reported that the rate of stocking emergency toilets was only about 20%. Portable and emergency toilet kits are sold at home improvement stores and online.

If someone in your home needs special care

For babies and small children, older people, people who have trouble chewing or swallowing, people with chronic illnesses and people with food allergies, the government PR site recommends at least 2 weeks of food that suits each person. After the Great East Japan Earthquake in 2011, some people with allergies could not get allergy-friendly food for more than a month. Families with a baby should also keep powdered or liquid milk, bottles, paper cups and disposable spoons, and jarred or pouch baby food that the child is used to.

What the numbers leave out

• "3 meals a day," "two-liter bottles" and "cases of six" are assumptions to make counting easier. They are not government figures.
• The 3 liters of water are for drinking and cooking. They do not cover washing, heating pouch meals in hot water or flushing.
• Medicine, hygiene items, pet food, flashlights and batteries are not included. Add them for your own situation.
• Think about where to store everything and how you will use the oldest food first. Some people build up their stock a little at a time on each shopping trip.

Frequently asked questions

Are 3 days of supplies enough?

The Government of Japan online PR site asks households to keep at least 3 days of food, and a week if possible. In past disasters it took more than a week in most cases for electricity, gas and water to return.

How much water does one person need?

About 3 liters a day, for drinking and cooking together. That is 9 liters for 3 days and 21 liters for a week. In two-liter bottles, that is 5 bottles for 3 days and 11 bottles for a week.

Can I store tap water?

Yes. The government PR site says tap water is disinfected with chlorine and can be used for drinking for about 3 days. Fill a clean container to the brim, close it tightly and keep it somewhere cool.

How many toilet uses should I stock?

The Ministry of Economy, Trade and Industry counts 5 uses per adult per day and recommends one week, which is 35 uses per person. For four people, that is 140 uses.

How much food is that?

There is no fixed amount. Counting 3 meals a day, it is 9 meals per person for 3 days and 21 for a week. Mix cans, pouches, rice, dried noodles and long-lasting vegetables for a balanced stock. The PR site gives a sample list.

Sources

• Government of Japan online PR site: how to start rolling stock for food (with the Ministry of Agriculture, Forestry and Fisheries; in Japanese)
• Ministry of Agriculture, Forestry and Fisheries: how to store water at home (in Japanese)
• Ministry of Agriculture, Forestry and Fisheries: food stock guide for disasters, summary edition (in Japanese)
• Cabinet Office magazine "Bousai" no. 111: toilet stock, by the Ministry of Economy, Trade and Industry (in Japanese)
• The amount you need depends on where you live, your building and your household. The numbers here are minimums based on government guidelines.

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Last updated: 2026-10-04