Work out how much water or fuel you need to hold and how many jerry cans that takes. Water is sized against a published humanitarian standard. Fuel is sized by distance or by running hours, depending on what you operate.
Result for this link
4 people × 3 days × 3 L a day, plus a 10% margin, is 40 litres: 2 × 20-litre cans, about 1% of a 20ft container.
Can used: 20L Stainless Steel Water Can. Danish Ministry of Civil Preparedness: 9 litres per person for three days, for drinking and some cooking.
Worked out by the calculator on this page. The same answer as JSON: /api/jerry-cans
| Basis | 500 people × 10 days × 15.0 L/person/day |
|---|---|
| Before margin | 75,000 L |
| Contingency | 10% (7,500 L) |
| Actually held | 82,500 L in 4,125 full cans |
| Container load | 4.8 × 20ft container or 2.1 × 40ft HQ |
Every default above is either a published standard, named where it is used, or a planning margin you can change. Nothing here is a quotation. Carton and container figures appear only for products where the factory has given us real dimensions; everything else says so.
How many litres of water or fuel you need to hold, and how many jerry cans, cartons and containers that comes to. Water starts from people, days and a rate per person per day. Fuel starts from distance and consumption for vehicles, or from running hours and burn rate for boats, generators and machinery.
Relief agencies and emergency planners stocking water, fleet and overland operators carrying fuel past the last pump, site managers sizing generator autonomy, and buyers turning a requirement into an order quantity.
Products behind the numbers: Fuel & Gas Cans, Water & Food-Grade Jerry Cans, NATO & Military Jerry Cans.
Each row runs the calculator's own defaults: the Sphere rates for water, the planning margins the tool shows for fuel, and the first can it suggests for that use. The last column is the share of a 20ft container the order fills, from that can's loading figure.
| Scenario | The sum | Margin | To hold | Cans | 20ft containers |
|---|---|---|---|---|---|
| Relief camp: 500 people for 10 days | 500 × 10 days × 15 L | 10% | 82,500 L | 4,125 × 20 L | 4.8 |
| Acute response: 1,000 people for 3 days | 1,000 × 3 days × 7.5 L | 10% | 24,750 L | 1,238 × 20 L | 1.5 |
| Overland: 500 km out and back | 500 km × 2 × 13 L/100 km | 25% | 163 L | 9 × 20 L | 1% |
| Generator: 72 hours of backup | 72 h × 4.5 L/h | 20% | 389 L | 20 × 20 L | — |
| Boat: 12 hours underway | 12 h × 4.5 L/h | 50% | 81 L | 5 × 20 L | 1% |
Water and fuel finish the same way: a quantity, a margin, then cans. They differ in where the quantity comes from. Water starts from people and days at a published rate. Fuel starts from distance or from engine hours, depending on what burns it.
Pick a country under “Your scenario” and the calculator loads that government’s advice for a household of four. Change the people for a school, a care home or a whole municipality; the rate and the days stay as the government sets them.
| Country | Per person a day | Days | Per person | 20 L cans, household of four | Calculator |
|---|---|---|---|---|---|
| Netherlands | 3 L | 3 | 9 L | 2 | Open |
| Sweden | 3 L | 7 | 21 L | 5 | Open |
| Norway | 2.86 L | 7 | 20 L | 5 | Open |
| Finland | 2 L | 3 | 6 L | 2 | Open |
| Denmark | 3 L | 3 | 9 L | 2 | Open |
| Germany | 2 L | 10 | 20 L | 5 | Open |
Read from each official page on 5 October 2026. Norway gives a weekly total of 20 litres, so its daily rate is 20 divided by 7. The can count includes the calculator’s 10 per cent margin.
If you know the generator’s size but not its burn rate, choose “Generators & backup power”, enter the kVA and the average load, and the calculator fills the burn rate. The estimate comes from a straight-line fit to Cummins diesel data sheets from 17 to 500 kVA, which it matches within about 6 per cent on average. Your own set’s plate figure is better where you have it.
| Diesel set | 50% load | 75% load | Full load | 20 L cans for 72 h at 75% |
|---|---|---|---|---|
| 20 kVA | 3.2 L/h | 4.3 L/h | 5.3 L/h | 19 |
| 50 kVA | 6.6 L/h | 9.2 L/h | 11.8 L/h | 40 |
| 100 kVA | 12.2 L/h | 17.4 L/h | 22.6 L/h | 76 |
| 200 kVA | 23.4 L/h | 33.8 L/h | 44.2 L/h | 147 |
Litres per hour = 1.0 + kVA × (0.008 + 0.208 × load), at a power factor of 0.8. The can count adds the calculator’s 20 per cent generator margin.
Safety advisers, trainers and trade bodies can embed it free. Paste the code into any web page. The tool updates when we update the rules, and the credit line links back here. Building software instead? The same answer comes as JSON from our free API.
Multiply the people by the days and by the litres each person needs a day, add a margin, then divide by the can size. The Sphere Handbook minimum is 15 litres per person per day for drinking, cooking and hygiene, so 100 people for 7 days need 10,500 litres, or 578 cans of 20 litres with a 10 per cent margin.
Take the burn rate at your working load from the set's plate, multiply it by the hours you must run without a delivery, and add a margin. A set burning 4.5 litres an hour for 72 hours needs 324 litres, 389 with a 20 per cent margin: 20 cans of 20 litres.
It depends on the can. The standard 20-litre steel NATO fuel can loads 852 to a 20ft container and 2,016 to a 40ft high cube. Across our range a 20ft takes from 548 to 3,000 cans, fewer for the large cans and more for the small ones.
Follow the one-third rule: a third to go out, a third to come back and a third in reserve. Size the running fuel from engine hours and add 50 per cent, which is the reserve third. Twelve hours at 4.5 litres an hour is 54 litres of running fuel and 81 litres to carry: 5 cans of 20 litres.
The standards and regulations this page relies on, at their issuing body. Where a market rule is named here, check the current revision before you specify against it.
The water rates in this tool are the headline figures from the Sphere Handbook's minimum standards in water supply, sanitation and hygiene promotion: 15 litres per person per day for drinking, cooking and hygiene, 7.5 litres in the acute phase for a short time, and up to 50 litres in urban or protracted contexts. Survival intake alone is 2.5–3 litres.
A truck burns fuel over distance. A boat, a generator and a tractor burn it over time, because the engine runs whether or not you are covering ground. Sizing a vessel's fuel from a distance figure is a common and expensive mistake, so the tool changes its inputs to match what you operate rather than asking everyone for kilometres.
Marine defaults to a 50% reserve, which is the one-third rule: a third out, a third back, a third untouched.
The calculator gives you a quantity. We will give you a specification sheet, a carton and container breakdown, and a price at your volume.