Propane Tank Runtime Calculator

Propane consumption varies by appliance BTU rating and usage hours. This calculator converts tank capacity to usable energy and estimates how long a tank will last.

Key conversion: 1 gallon of propane = 91,452 BTU of energy Burn Time (hours) = (Tank Gallons × 91,452) / Appliance BTU Rating

Common tank sizes:

Note: the gallon figures above are already the usable amount. Tanks are never filled 100% full, because propane expands with heat and needs a vapour space above the liquid, so a filler stops at about 80%. A “20 lb” tank holds 20 lb of propane at that 80% fill, which is 4.7 gallons. Do not knock another 20% off the numbers on this page. That has already been done for you.

Worked example, BBQ grill:

• 20 lb tank = 4.7 gallons usable
• Medium gas grill: ~35,000 BTU/hour
• Burn time: (4.7 × 91,452) / 35,000 = 12.3 hours of grilling

Worked example, patio heater:

• 20 lb tank = 4.7 gallons
• Patio heater: ~50,000 BTU/hour
• Burn time: (4.7 × 91,452) / 50,000 = 8.6 hours

Common appliance BTU ratings:

• Portable camp stove: 7,500–10,000 BTU/hr
• Standard gas grill: 25,000–60,000 BTU/hr
• Patio / tower heater: 40,000–50,000 BTU/hr
• Home furnace: 60,000–120,000 BTU/hr
• Pool / spa heater: 100,000–400,000 BTU/hr