Calculators / Outdoor kitchen

How long will a propane tank last on my grill?

Pick the tank and put in your grill's Btu rating. You get the hours, and the number of cookouts a tank lasts.

Updated November 2026 · How we check our numbers

A full tank lasts about

21.6 hours

A 20 lb tank holds about 4.7 gallons, 432,397 Btu. At 50% of a 40,000 Btu/h grill that's 21.6 hours, about 21 cookouts of 1 h.

Run time: 21.6 h
Propane: 4.7 gal20 lb
Burning: 20,000 Btu/h
Cookouts: 211 h each

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Estimate for planning only, not professional advice. Check the manufacturer’s instructions, your local code and a licensed professional before you buy, build or install. Use at your own risk. Terms.

gallons = 20 lb ÷ 4.23 lb/gal = 4.7

heat = 4.7 × 91,452 Btu = 432,397 Btu

hours = 432,397 ÷ (40,000 × 50%) = 21.6

By how hard you run it

40,000 Btu/h grill

25% of full output10,000 Btu/h
43.2 h
50% of full output20,000 Btu/h
21.6 h
75% of full output30,000 Btu/h
14.4 h
Every burner on high40,000 Btu/h
10.8 h

Grill Btu

Use the total of the main burners on the rating plate or spec sheet. Add a side burner or rotisserie burner if you'll run them too.

The 4.23 figure

Propane's weight per gallon isn't printed on a government page, so we worked it out from NIST's density for liquid propane at 60°F. EIA gives the 91,452 Btu per gallon.

How we work it out

hours = tank lb ÷ 4.23 lb/gal × 91,452 Btu/gal ÷ (grill Btu/h × share you use)

EIA puts propane at 91,452 Btu a gallon. Liquid propane weighs about 4.23 lb a gallon (from NIST's density at 60°F), so a 20 lb tank holds about 4.7 gallons, roughly 432,000 Btu. A 40,000 Btu/h grill at half output burns 20,000 Btu an hour: about 21½ hours.

Where the numbers come from

Outdoor kitchen

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