Propane fireplaces burn the same BTU math as natural gas, billed in gallons instead of therms. Enter your tank or meter price — national averages miss delivery fees and winter spikes.
Gallons from BTU
Gallons per hour ≈ fireplace fuel BTU/hr ÷ 91,500. A 30,000 BTU/hr unit treated as 75% efficient heat output implies about 40,000 BTU of propane per hour, or about 0.44 gallons. At $2.67/gallon that is about $1.17 per hour before a pilot light.
Why propane often costs more per hour
A gallon of propane holds a little under one therm of energy, and residential propane per gallon is typically priced higher than a therm of utility gas. The comparison table uses the same fireplace hours on both fuels so the gap is visible.
Pilot lights still matter
A standing 800 BTU/hr pilot is a small hourly number that becomes a noticeable monthly gallon draw if it runs 24/7. Toggle it on in the calculator if your unit is not millivolt-off or electronic ignition.
Propane fireplace calculator
4 h
30 days
US default $2.67/gallon. Using default.
Default 720 hours (hours/day × 180 days).
Per hour
$1.17
Main burner
Per day
$4.67
4 h on
Per month
$140.07
Per season
$840.39
720 h
Fuel use: 0.437 gallons/hour of burner time (40,000 BTU/hr after assumptions).
GasFireCost is unofficial. It estimates fuel cost from BTU ratings and the rates you enter. It does not include taxes, utility customer charges, tank rental, or installation. No affiliation with OEMs or utilities. Verify rates with your utility or propane supplier. See methodology.
Month
$140.07
Season
$840.39
Frequently asked questions
How much does a gas fireplace cost per hour?+
With the site’s US defaults (30,000 BTU/hr, 75% efficiency assumption, $1.47/therm), a natural gas fireplace is about $0.59 per hour. The same unit on propane at $2.67/gallon is about $1.17 per hour. Your bill depends on nameplate BTU, local rates, and hours used.
How many BTU are in a gallon of propane?+
This calculator uses 91,500 BTU per gallon as a round US planning number. The US Energy Information Administration’s HD-5 propane conversion is 91,452 BTU per gallon (higher heating value). The difference is under 0.1% and does not change a household estimate in a meaningful way.
Is natural gas cheaper than propane for a fireplace?+
Usually, on a per-BTU basis, yes — at these US defaults natural gas is about half the hourly cost of propane for the same fireplace. Propane can still be the practical fuel where there is no gas main. Compare with your actual $/therm and $/gallon, not national averages.
How much does a standing pilot light cost?+
A 600–1,000 BTU/hr pilot running 24 hours uses about 0.14–0.24 therms per day on natural gas, or roughly $6–$11 per month at $1.47/therm before the main burner. Enable “pilot light on” in the calculator and set BTU/hr from your manual.