How Long Will a Propane Tank Last?

Propane delivers about 91,500 BTU per gallon, so runtime is appliance BTU rating ÷ 91,500 = gallons per hour at full fire. A 100,000 BTU/hr furnace burns about 1.1 gal/hr while firing; at a realistic 40–50% winter duty cycle that's 11–13 gallons a day of heating in cold weather.

The same math scales down: a 30,000 BTU fireplace insert is ~0.33 gal/hr; a 60,000 BTU pool heater ~0.66 gal/hr; a 12,000 BTU cooktop burner barely registers. Whole-home usage in heating season commonly lands between 3 and 10 gallons a day depending on climate, insulation and house size.

Worked example: a 500-gallon tank filled to its 80% maximum holds 400 gallons. At 6 gal/day of winter usage that's about nine weeks; at 2 gal/day shoulder-season usage, over six months. A 120-gallon tank (96 usable) feeding only a water heater and range often runs most of a year.

Track your own burn the reliable way: gauge readings a week apart, converted to gallons (gauge % × water capacity — see reading the gauge), divided by days. Then size reorders with the propane charts.