Propane usage calculator
This propane usage calculator turns the size of your tank and the BTU rating of your appliance into run time. A full 20 lb tank on a 30,000 BTU/h grill running at full flame lasts about 13 to 14 hours.
Source: NIST Chemistry WebBook, SRD 69 – Propane: M = 44.0956 g/mol, ΔcH°gas = −2219.2 ± 0.46 kJ/mol (Pittam and Pilcher, 1972), Tboil = 231.1 K (read 10.10.2026). Updated: .
How it is calculated
Run time = propane in the tank × energy per pound ÷ appliance rating. The energy per pound comes from the heat of combustion listed in the NIST Chemistry WebBook: propane releases 2,219.2 kJ per mole (44.0956 g). That is a gross heating value of 21,637 BTU per pound. Subtracting the heat carried away in the water vapor (44.004 kJ per mole of water) leaves a net heating value of 19,921 BTU per pound.
Example run times (propane, full flame)
| Tank | Rating | Run time |
|---|---|---|
| 20 lb | 10,000 BTU/h | 39.8–43.3 h |
| 20 lb | 30,000 BTU/h | 13.3–14.4 h |
| 20 lb | 60,000 BTU/h | 6.6–7.2 h |
The range exists because an input rating can be stated on the gross or the net heating value of the gas; the lower number is the cautious estimate. A 30,000 BTU/h grill is 8.79 kW and uses 629 to 683 g (1.39 to 1.51 lb) of propane per hour. If you grill one hour a day, a 20 lb tank lasts 13.3 to 14.4 days. A 1 lb camping cylinder on a 10,000 BTU/h stove runs about 2 hours.
Good to know
- If the label lists consumption in grams per hour, that is the most direct figure: choose “Consumption on the label”.
- Grills, patio heaters and stoves rarely run at full flame all the time, so real-world run time is usually longer.
- Propane boils at −42 °C (−44 °F) and butane at about 0 °C (NIST), so butane canisters struggle in the cold while propane keeps working.
- Safety: Ready.gov says camp stoves and grills should always be used outdoors, at least 20 feet from windows, and a gas stovetop or oven should never be used to heat a home – carbon monoxide can build up.
To convert BTU, kWh and joules, use the energy converter; for party food amounts, see how much meat per person.
Frequently asked questions
How long will a 20 lb propane tank last on a grill?
At 30,000 BTU/h and full flame about 13 to 14 hours; at 60,000 BTU/h about 7 hours. Medium or low settings stretch it further.
How many BTU are in a pound of propane?
About 21,637 BTU gross (higher heating value) or 19,921 BTU net, calculated from the NIST heat of combustion.
How much propane does a 1 kW appliance use per hour?
About 72 to 78 g (0.16 to 0.17 lb) per hour.
Why is there a range instead of one number?
Ratings can be based on the gross or the net heating value. The calculator shows both; the shorter time is the cautious estimate.
How do I convert BTU/h to kW?
1 BTU/h equals 0.2931 W (NIST), so 30,000 BTU/h is about 8.79 kW.
Does butane last longer than propane?
Per pound hardly at all: butane has 13.75 kWh/kg gross, propane 13.98 kWh/kg – a difference of about 1.6 %.
Sources and legal basis
- NIST Chemistry WebBook, SRD 69 – Propane: M = 44.0956 g/mol, ΔcH°gas = −2219.2 ± 0.46 kJ/mol (Pittam and Pilcher, 1972), Tboil = 231.1 K (read 10.10.2026)
- NIST Chemistry WebBook, SRD 69 – Butane: M = 58.1222 g/mol, ΔcH°gas = −2877.5 ± 0.63 kJ/mol (Pittam and Pilcher, 1972), Tboil = 273 ± 1 K (read 10.10.2026)
- NIST Chemistry WebBook, SRD 69 – Water: ΔfH°gas = −241.826 kJ/mol, ΔfH°liquid = −285.830 kJ/mol (heat of vaporization at 25 °C: 44.004 kJ/mol) (read 10.10.2026)
- NIST SP 811, Appendix B.8: 1 lb = 0.453 592 37 kg; 1 Btu (IT)/h = 0.293 071 1 W (read 10.10.2026)
- BBK (German Federal Office of Civil Protection), Vorsorgen für Krisen und Katastrophen guide, pp. 22–23: camping stoves with gas cartridges and gas or charcoal grills outdoors only; indoors only appliances approved for it; with too little oxygen carbon monoxide can form (read 10.10.2026)
- Ready.gov (FEMA), Power Outages: generators, camp stoves or charcoal grills should always be used outdoors and at least 20 feet away from windows; never use a gas stovetop or oven to heat your home (read 10.10.2026)
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