BTU per Gallon of Propane
A gallon of propane contains 91,452 BTU of energy, the standard conversion factor the US Energy Information Administration publishes for propane (higher heating value). That works out to about 21,500 BTU per pound and roughly 2,516 BTU per cubic foot of vapor.
How much energy is in a gallon of propane?
The single number to remember is 91,452 BTU per gallon. This is the conversion factor the EIA uses to turn gallons of propane into British thermal units for cross-fuel energy comparison, and it is the figure behind every per-BTU calculation on this site. It is a gross (higher) heating value, measured at standard conditions.
Pure propane has a slightly higher combustion energy of 91,690 BTU per gallon. Consumer propane is HD-5 grade, which allows up to 5 percent propylene (lower energy, 84,500 BTU per gallon) with the balance mostly butane (higher, 102,800 BTU per gallon). Those offset, so HD-5 delivers very close to the nominal 91,500 BTU per gallon that appliance and energy calculations assume. Commercial HD-10 propane, with more propylene, runs marginally lower at around 90,300 BTU per gallon. Our HD-5 propane specification page covers the grade detail.
BTU per pound, per cubic foot, and per gallon
The same energy content can be expressed three ways, depending on whether you measure propane by liquid volume, by weight, or as vapor:
| Unit | BTU (higher heating value) | How it is derived |
|---|---|---|
| 1 gallon (liquid) | 91,452 BTU | EIA published conversion factor |
| 1 pound | ~21,500 BTU | 91,452 over ~4.24 lb per gallon |
| 1 cubic foot (vapor) | ~2,516 BTU | ~36.4 cu ft of vapor per gallon |
| 1 million BTU (MMBtu) | 1,000,000 BTU | = 10.93 gallons of propane |
Per-pound energy content (~21,500 BTU) is temperature-stable, which is why bulk, autogas, and forklift propane is often metered by weight rather than by gallon. Liquid propane expands and contracts with temperature, so dealers temperature-compensate gallons on a delivery ticket to keep the energy you pay for consistent.
Gross vs net heating value
The 91,452 BTU per gallon figure is the gross, or higher, heating value (HHV). It includes the heat that would be released if the water vapor produced by combustion were condensed back to liquid. Conventional non-condensing furnaces and water heaters do not recover that, so the heat they actually deliver is closer to the net, or lower, heating value (LHV) of about 84,250 BTU per gallon, roughly 8 percent lower. Cross-fuel comparisons use the gross figure for every fuel so the comparison stays consistent; a condensing appliance recovers part of the gap.
How propane compares to other fuels per BTU
Energy content is what makes per-gallon, per-therm, and per-kWh prices comparable. On a common BTU basis:
| Fuel | Energy content (gross) | Per-BTU comparison |
|---|---|---|
| Propane | 91,452 BTU per gallon | vs natural gas |
| Heating oil | ~138,500 BTU per gallon | vs heating oil |
| Natural gas | 100,000 BTU per therm (~1,030 BTU/cu ft) | vs natural gas |
| Electricity | 3,412 BTU per kWh | vs electricity |
A gallon of heating oil holds about 1.5 times the energy of a gallon of propane, which is why heating oil prices per gallon look high until you put them on a per-BTU footing.
What it means for your propane bill
Because propane energy content is fixed at 91,452 BTU per gallon, the per-gallon price translates directly to a per-BTU heating cost. At the latest US residential price of $2.674 per gallon (week ending 30 March 2026), propane costs about $29.24 per million BTU. Track the live price on the propane price per gallon homepage, see the per-fuel math on the price per BTU comparisons, or estimate a fill on the fill cost calculator.
FAQ
How many BTU are in a gallon of propane?
91,452 BTU per gallon, the EIA standard conversion factor for propane (higher heating value). Pure propane is 91,690 BTU per gallon; HD-5 consumer propane sits at the nominal 91,500 BTU per gallon.
How many BTU are in a pound of propane?
About 21,500BTU per pound, the per-gallon figure divided by propane's liquid density of roughly 4.24 pounds per gallon. Unlike the per-gallon figure, the per-pound value does not shift with temperature.
What is the BTU per cubic foot of propane?
Roughly 2,516 BTU per cubic foot of vapor. One gallon of liquid propane expands to about 36.4 cubic feet of vapor. Natural gas, by comparison, holds about 1,030 BTU per cubic foot.
Is propane BTU measured gross or net?
The 91,452 figure is gross (higher heating value). The net (lower heating value) most non-condensing appliances deliver is about 84,250 BTU per gallon, around 8 percent lower.
Sources: US Energy Information Administration, British thermal units (Btu) and energy conversion calculators. Energy-content figures verified 29 June 2026. By Oliver Wakefield-Smith.