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Propane Tank Size, Burn Time & Vaporization Calculator

Calculate propane liquid vaporization rate (BTU/hr at 0°F to 40°F), run time in hours/days, and tank sizing (100 lb, 250 gal, 500 gal, 1,000 gal) to prevent tank freeze-ups.

e.g. 100k furnace + 40k water heater = 140,000 BTU/hr
Propane tanks are legally filled to 80% maximum

Calculation & Generation Results

Vaporization Capacity at Selected Temp: 278,000 BTU/hr Safe (Exceeds 140k BTU demand - No Freeze-Up)
Continuous Full-Fire Run Time: 156 Hours (6.5 Days) ~18 - 25 Days at normal winter cycling duty
Liquid Propane in Tank: 240 Gallons (21.9M Total BTU)
Propane Fuel Consumption Rate: 1.53 Gallons / hour at full fire

About This Tool

Calculate propane liquid vaporization rate (BTU/hr at 0°F to 40°F), run time in hours/days, and tank sizing (100 lb, 250 gal, 500 gal, 1,000 gal) to prevent tank freeze-ups.

Frequently Asked Questions

Why do propane tanks freeze over in winter?

Liquid propane boils and converts into gas by absorbing heat from ambient air through the tank's steel walls. When appliance BTU demand exceeds the tank's heat transfer surface area, the tank chills below -44°F, frost blankets the exterior, and pressure drops to zero.

How many BTUs are in a gallon of liquid propane?

One US gallon of liquid propane contains approximately 91,500 BTUs of energy (21,548 BTUs per pound).

Why are propane tanks only filled to 80% capacity?

Under NFPA 58 rules, propane tanks are filled to a maximum of 80% to allow a 20% expansion headspace for liquid volume swings caused by summer heat.

What size propane tank is required for whole-home heating?

A 500-gallon tank is the standard minimum size for whole-home heating and standby generators in cold northern climates to ensure adequate vaporization surface area during sub-zero cold snaps.