Propane Grill Calculator
Calculate how many 20-lb propane tanks you need per grilling season from your grill BTU rating, heat setting, and how often you cook.
Shows hours per tank.
BBQ grill propane usage depends on the grill’s BTU output, how many burners you use, and how long you cook. Knowing your consumption rate helps you avoid running out mid-cookout and plan refills or tank swaps.
Formulas: BTU Consumption Rate = Grill BTU Rating × Fraction of Max Setting Propane Used (lbs) = BTU Consumed ÷ 21,548 BTU/lb Propane Used (gallons) = BTU Consumed ÷ 91,452 BTU/gallon Hours per Tank = 20 lbs ÷ Propane Burn Rate (lbs/hr)
Propane energy content:
- 1 gallon of liquid propane = 91,452 BTU
- 1 lb of propane = 21,548 BTU
- A standard 20-lb tank holds approximately 4.7 gallons
- A full 20-lb tank contains approximately 430,000 BTU
Typical gas grill BTU ratings:
| Grill Size | Burners | Total BTU |
|---|---|---|
| Small 2-burner | 2 | 20,000–30,000 BTU |
| Mid-size 3-burner | 3 | 30,000–40,000 BTU |
| Large 4-burner | 4 | 40,000–60,000 BTU |
| Professional 6-burner | 6 | 60,000–90,000 BTU |
Actual cooking often uses 50–70% of maximum BTU (medium heat for most grilling).
Worked example: 3-burner grill rated at 36,000 BTU total (12,000 BTU/burner). You grill for 2 hours with all 3 burners on medium, which is the 65% setting.
BTU used = 36,000 × 0.65 × 2 = 46,800 BTU Propane used = 46,800 ÷ 91,452 = 0.51 gallons Propane by weight = 46,800 ÷ 21,548 = 2.17 lbs
How long does a 20-lb tank last? Total BTU in tank = 20 × 21,548 = 430,960 BTU At 46,800 BTU per 2-hour session: Sessions = 430,960 ÷ 46,800 = about 9 sessions, or 18.4 hours of cooking
Those are the exact numbers the calculator returns if you enter 36,000 BTU on the medium setting, so you can check it against this by hand.
Refill and exchange prices swing a lot by region and by season, and an exchange cage at a supermarket typically costs more per pound than getting your own tank refilled at a propane dealer, because the swap tanks are usually filled to 15 lbs rather than 20. Enter whatever you actually pay in the cost field and the calculator will use your number rather than a guess of ours.
Checking tank level without a gauge: Pour warm water down the side of the tank. Feel for where it changes from warm to cool. The cool line is where the liquid propane level sits. Weigh the tank: subtract the tare weight (stamped “TW” on the collar, usually 17–18 lbs) from total weight to get propane remaining.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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