Propane Usage & Cost Calculator
Estimate how much propane your appliances burn and what it costs per day, month, season or year — from each appliance’s BTU rating, run time and average firing rate, with prices per gallon, liter, pound or kilogram, tank refill timing and an electric heating comparison.
How it works
Gallons/day = Σ (BTU/hr × hours a day × firing rate) ÷ 91,500 BTU/gal · Cost/day = gallons × price per gallon (a price per liter, lb or kg is converted at 3.785 L/gal and 4.24 lb/gal) · Total = daily × days · Tank lasts = usable gallons ÷ gallons/day · Electric comparison: useful heat = BTU × efficiency ÷ 3,412 BTU/kWh, × electricity price (÷ COP for a heat pump)
Propane carries about 91,500 BTU of energy per gallon, so an appliance’s fuel use is its firing rate times how long it burns, divided by that energy content. A 30,000 BTU/hr heater running five hours consumes 150,000 BTU, or roughly 1.6 gallons a day. Multiplying by price and days projects the cost across a month, a heating season or a year; the period table shows each at once, in gallons and pounds. Pick a typical appliance or enter the rating from its label, and switch on more appliances to total a household — say a furnace, water heater and range. The tank option shows how long a full cylinder or tank lasts at that rate and how many refills the period needs. For space or water heating, the comparison shows what the same useful heat would cost from electric resistance heat or a heat pump, and the propane price at which a heat pump stops being cheaper. Enter prices per gallon, liter, pound or kilogram — whatever your supplier uses.
Worked example
A 30,000 BTU/hr heater run 5 hours a day uses 30,000 × 5 ÷ 91,500 ≈ 1.64 gallons daily. At $3.00/gal that is about $4.92 a day, so over 30 days roughly 49 gallons and $148. A full 20 lb cylinder (4.72 gallons) lasts about 2.9 days at that rate. Delivering the same heat with a 90% efficient heater means 135,000 useful BTU a day — 39.6 kWh — which would cost $201.78 over 30 days with electric resistance heat at $0.17/kWh, or $67.26 with a heat pump at a COP of 3.
Sources: U.S. EIA — Heating oil and propane update (residential prices) · U.S. EIA — Energy units and calculators
Frequently asked questions
How long will a 20 lb propane tank last?
A standard 20 lb grill tank holds about 4.7 gallons, or roughly 430,000 BTU. Divide that by your appliance’s hourly BTU use: a 30,000 BTU/hr burner would run about 14 hours on a full tank. Choose the tank under More options to see it for your own use pattern.
Do appliances burn at their full rating constantly?
Not usually. Thermostatically controlled heaters and furnaces cycle on and off, so their average draw is below the nameplate rating. Enter the hours the burner is actually lit, or set an average firing rate for a burner turned down, such as a grill on medium.
Why 91,500 BTU per gallon?
That is the widely used energy content of liquid propane (the U.S. EIA uses 91,452). It varies slightly with temperature and blend, but 91,500 BTU/gal — about 21,600 BTU per pound — is the standard figure for sizing and cost estimates.
How much propane does a house use?
It depends mainly on heating. A home that heats with propane commonly uses 500–1,000 gallons a year or more in cold climates, while one that uses it only for a water heater, range and dryer may use 200–300. Add your appliances with their hours to estimate your own figure.
Is propane cheaper than electric heat?
Compared with electric resistance heat, usually yes: a gallon of propane holds about 26.8 kWh of energy. Compared with a heat pump it often is not. Switch on the electric comparison to see both for your prices, along with the propane price at which the two cost the same.
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This calculator is for educational purposes. Double-check important results before acting on them.