How Long Will Propane Last is a free calculator for anyone who runs on propane: grill and RV owners, patio heater users and the millions of homes heated with a propane tank. It answers one question well: how long will the propane in my tank last, and when should I order more?
Where the numbers come from
Propane holds about 91,500 BTU per gallon. Appliance use comes from the BTU rating on the data plate and how long it runs. For home heating, the calculator estimates heat loss from floor area, insulation and outdoor temperature, then divides by furnace efficiency. The default price is the U.S. Energy Information Administration weekly residential average; enter your own for an exact cost.
Results are estimates for planning. Your supplier’s readings and your appliance manuals come first, and it is always wise to order before the gauge reaches 20%.