Field tool
Propane Runtime Calculator
How long a 1 lb bottle, a 20 lb grill tank or a 100 lb cylinder lasts on a camp stove, heater or grill. Hours and days, with exchange tanks included.
Run time
43 hours
21.6 days at 2 hours a day
About 432,000 BTU on hand
How the math works
A pound of propane holds about 21,600 BTU, and a gallon about 91,500 BTU. A burner rated at 10,000 BTU per hour on high uses that much heat every hour it runs at full flame. Divide the BTU in the tank by the burner's rating and you get the hours.
These are estimates. Real run times are usually a bit shorter: tanks are seldom perfectly full, wind steals heat from a stove, and a burner turned down to simmer uses less than its rating. Treat the result as a planning number, not a promise.
How long does a 20 lb propane tank last?
Hours of run time at full setting, worked out from about 21,600 BTU per pound.
| Appliance | 1 lb bottle | Exchange 20 lb tank (about 15 lb) | Refilled 20 lb tank | 100 lb cylinder |
|---|---|---|---|---|
| Camp stove, 1 burner on high | 2.2 h | 32 h | 43 h | 216 h |
| Camp stove, 2 burners on high | 1.1 h | 16 h | 22 h | 108 h |
| Portable heater on low | 5.5 h | 81 h | 108 h | 540 h |
| Portable heater on high | 2.5 h | 36 h | 48 h | 240 h |
| Large portable heater on high | 1.2 h | 18 h | 24 h | 120 h |
| Gas grill, 3 burners on high | 0.7 h | 11 h | 14 h | 72 h |
Safety: Camp stoves and grills run outdoors only, every time. They make carbon monoxide, which you can't see or smell. Only a heater labelled for indoor use belongs inside, with a window cracked and a battery-powered carbon monoxide alarm in the room. Big tanks always stay outside. See propane exchange vs refill for safe storage.
Cold weather cuts what a tank can deliver
Propane has to boil off inside the tank before it burns. In hard cold, a small tank can't make vapor as fast as a big burner wants it, so the flame drops even though there is fuel left. Little 1 lb bottles suffer most. A larger tank, kept out of the wind, keeps up better. This changes the flame, not the total BTU, so the calculator's hours still hold as a ceiling.
Frequently asked questions
How long does a 20 lb propane tank last?
A full 20 lb tank holds about 430,000 BTU. That is about 43 hours on a 10,000 BTU stove burner on high, or about 48 hours on a heater set to 9,000 BTU. An exchange tank usually holds about 15 lb, so expect about a quarter less.
How much propane is in an exchange tank?
Most exchange tanks hold about 15 lb of propane in a cylinder built for 20 lb. A tank you refill at a station is filled to about 20 lb, so you get more fuel for the same cylinder.
How many BTU are in a pound of propane?
About 21,600 BTU per pound, or about 91,500 BTU per gallon. A gallon of propane weighs about 4.2 lb.