How Long a Propane Tank Will Last Based on Usage

Last updated July 2, 2026

Propane runtime depends on tank size, the BTU consumption rate of the appliance or appliances drawing from it, and the conversion factor that one gallon of propane contains approximately 91,500 BTUs. For a standard 100-pound propane tank, which holds approximately 23.6 gallons, powering a 30,000 BTU heater running continuously, the tank provides roughly 72 hours of continuous runtime. calculated by dividing total available BTUs by the BTU consumption rate per hour. Most usage is not continuous, however, so the practical runtime for intermittent use, such as a heater cycling on and off to maintain temperature, extends considerably longer than the continuous-use figure suggests.

For whole-house propane heating systems using a larger 500-gallon tank, the calculation scales accordingly but follows the same underlying formula. A typical home furnace rated at 80,000 BTUs running during an average winter day might consume 6 to 8 gallons over 24 hours during cold weather, meaning a 500-gallon tank filled to its safe capacity of 400 gallons could provide 50 to 65 days of continuous winter heating in moderate cold, with actual runtime extending longer in milder weather when the furnace cycles less frequently. Tank gauges showing percentage full provide the most reliable real-time tracking, since they account for actual remaining propane rather than relying solely on calculated estimates.

The calculation shows propane runtime by converting your tank's gallon capacity to total BTUs available, then dividing by your appliance's BTU consumption rate per hour. For variable or intermittent use such as home heating, treat the continuous-use calculation as a worst-case minimum and expect actual runtime to extend longer based on cycling patterns and outdoor temperature.