Gas Appliance Running Cost Calculator
What a propane or natural gas appliance costs to run an hour from its BTU rating, and how long a propane tank lasts.
Result
Cost per hour: $0.98Estimate
Fuel burned at the rated input, not heat delivered. Appliances that cycle or run on low burn less; the maker’s instructions cover safe use and venting.
- Cost for the hours of use
- $9.84Estimate
- Gas energy burned per hour
- 30,000 Btu (8.8 kWh)
- Propane burned per hour
- 1.387 lb (0.629 kg)Estimate
- Liquid propane burned per hour
- 0.328 gal (1.242 L)Estimate
- Hours a full tank lasts
- 14.4Estimate
https://calcgallery.com/energy-utilities/gas-appliance-running-cost-calculator/
Results are estimates based on the ratings, usage and prices you enter. Actual consumption, losses, tariffs and equipment performance vary. Check your bill, meter and manufacturer information before relying on the result. Read the full disclaimer
How to use the Gas Appliance Running Cost Calculator
- Choose propane or natural gas.
- Enter the input rating from the appliance's label or manual, in BTU per hour or kilowatts.
- Enter the hours you expect to run it.
- For propane, choose how it is priced, enter the price and the amount of propane in a full tank.
- For natural gas, choose the unit your bill uses and enter the price per unit.
How it is calculated
energy an hour = input rating × share of full flame × 1 hourpropane = energy ÷ 91,452 Btu per gallon × 4.2285 lb per gallon for the weightnatural gas = energy ÷ 1,036 Btu per cubic foot (therms = energy ÷ 100,000 Btu)cost an hour = fuel in the priced unit × pricehours on a tank = propane in the tank ÷ pounds burned an hourThe heat contents are the U.S. Energy Information Administration’s conversion factors: 91,452 Btu in a gallon of propane, 1,036 Btu in a cubic foot of natural gas, and 100,000 Btu in a therm. The weight of propane, 506.687 kg per cubic metre (4.2285 lb per US gallon), is the NIST Chemistry WebBook’s density of liquid propane at 60 °F, the temperature a propane gallon is measured at.
What the answer leaves out
The appliance is taken as burning its full rating, or the share you set, for every hour entered. Pilot lights, electric blowers and igniters are not included, and neither is how much of the heat reaches the room. Commercial propane and each utility’s natural gas vary slightly from the average heat contents used here. Follow the maker’s instructions for safe use and ventilation of any gas appliance.
With your numbers
- Energy an hour = 30,000 BTU/h × 100% × 1 h = 30,000 Btu
- Propane = 30,000 Btu ÷ 91,452 Btu a gallon = 0.328 gal an hour
- Cost an hour = fuel in the priced unit × $3.00 = $0.98
Quick reference
Fuel burned at the rated input, not heat delivered. Appliances that cycle or run on low burn less; the maker’s instructions cover safe use and venting.
| Example | Cost per hour |
|---|---|
| 20 lb tank on a 30,000 BTU/h grill | $0.98 |
| 40,000 BTU/h patio heater on a 20 lb tank | $1.31 |
| 10,000 BTU/h camp stove, $1.25 per lb | $0.58 |
| 60,000 BTU/h fire pit on a 100 lb tank | $1.97 |
| 30,000 BTU/h gas fireplace, $1.50 per therm | $0.45 |
| 80,000 BTU/h furnace, $1.40 per ccf | $1.08 |
| 9 kW propane heater, 1.00 per litre | €1.27 |
| 10 kW gas fire, 0.10 per kWh | €1.00 |
Where the numbers come from
The fixed figures this calculator relies on, and the published source each one was checked against. How the calculators are built and checked
3 sources
U.S. Energy Information Administration, Units and calculators explained, table "Sample Btu conversion factors": "Propane 1 gallon=91,452 Btu"; footnote: "Current conversion factors are updated annually in Appendix A of the Monthly Energy Review." https://www.eia.gov/energyexplained/units-and-calculators/; the propane factor itself is fixed: Monthly Energy Review (August 2026), Appendix A, Table A1, "Propane 3.841" million Btu per barrel (3,841,000 ÷ 42 = 91,452), https://www.eia.gov/totalenergy/data/monthly/pdf/mer_A_FULL.pdf
Used for
- Heat content of liquid propane: 91,452 Btu per US gallon, from EIA’s fixed factor of 3.841 million Btu per 42-gallon barrel.
NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, propane (C74986), saturation properties at 60 °F: pressure 107.714 psia, liquid density 506.687 kg/m³ (31.6315 lbm/ft³). https://webbook.nist.gov/cgi/fluid.cgi?Action=Data&Wide=on&ID=C74986&Type=SatP&Digits=6&TLow=60&THigh=60&TInc=1&TUnit=F&PUnit=psia&DUnit=kg%2Fm3&RefState=DEF&HUnit=kJ%2Fkg&WUnit=m%2Fs&VisUnit=uPa*s&STUnit=N%2Fm
Used for
- Density of liquid propane at 60 °F, the temperature the LPG gallon is defined at: 506.687 kg/m³, 4.2285 lb per US gallon. Pure propane; commercial grades differ slightly.
U.S. Energy Information Administration, Units and calculators explained, table "Sample Btu conversion factors": "Natural gas 1 cubic foot=1,036 Btu 1 therm=100,000 Btu". https://www.eia.gov/energyexplained/units-and-calculators/; the same 1,036 is the total-consumption factor for 2025 (preliminary) and 2026 (estimate) in the Monthly Energy Review (August 2026), Appendix A, Table A4 (end-use sectors 1,037), https://www.eia.gov/totalenergy/data/monthly/pdf/mer_A_FULL.pdf
Used for
- Heat content of natural gas: 1,036 Btu per cubic foot. Each utility's gas differs; the bill's therm factor is its own figure.
Common questions about the Gas Appliance Running Cost Calculator
- How long will a 20 lb propane tank last?
- Divide the propane in the tank by what the appliance burns an hour. At EIA's 91,452 Btu per gallon and 4.23 lb per gallon, a pound of propane holds about 21,600 Btu, so 20 lb runs a 30,000 BTU/h grill for about 14 hours at full flame, and a 40,000 BTU/h patio heater for about 11. Many exchange cylinders are filled to 15 lb, not 20, which cuts those times by a quarter.
- How much does it cost to run a patio heater per hour?
- A 40,000 BTU/h heater at full flame burns about 0.44 gallons (1.85 lb) of propane an hour. Multiply by your propane price per gallon or pound. Running it on a lower setting burns proportionally less; set the share of full flame under More options.
- How is natural gas priced per therm or per ccf?
- A therm is 100,000 Btu, the definition EIA uses. A ccf is 100 cubic feet of gas, which at EIA's average of 1,036 Btu per cubic foot is about 1.04 therms. Your utility's gas may differ a little, and the bill's therm factor gives its own figure.
- Is the BTU rating the heat I get?
- No. The rating on the label is the fuel the appliance burns. How much of that reaches you as heat depends on the appliance: a vented fireplace sends some up the flue, an outdoor heater loses heat to the wind. This page costs the fuel burned, which is what the bill measures.
- Can I use this for a furnace?
- Yes, for the hours the burner is actually lit. A furnace cycles on and off, so its running hours are much less than the hours in a day. For a whole season's heating cost, the heat pump versus furnace calculator works from an annual heating load instead.