How Much Does It Cost to Run Gas Logs?
Almost every page you'll find answers a different question — what gas logs cost to buy. This one answers what they cost to burn. Put in your set's BTU rating and the rate off your own gas bill, and you get the number in fuel and in dollars. No sign-up, no email.
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What your fire costs per hour
Two numbers decide it: how many BTUs per hour your set burns (printed on the burner tag, the rating plate or the spec sheet) and what your utility charges per unit. Everything else is arithmetic — and we show that arithmetic below the tool, so you can check us.
We deliberately don't pre-fill a gas price. Rates swing by state, by utility and by month, and a made-up national average would give you a made-up answer. Leave the rate blank and you still get your fuel consumption; type the rate from your bill and you get dollars. Natural gas bills often list CCF rather than therms — your bill carries the conversion (it is close to, but not exactly, 1 therm per CCF).
How much fuel a gas log set actually burns
This table has no prices in it on purpose — these are pure conversions, true in every state and every year. Find the row nearest your set's rating, then multiply by whatever your utility charges.
| Burner rating | Natural gas per hour | Propane per hour | Propane per hour (lbs) |
|---|---|---|---|
| 30,000 BTU/hr | 0.30 therm | 0.33 gal | 1.4 lb |
| 45,000 BTU/hr | 0.45 therm | 0.49 gal | 2.1 lb |
| 60,000 BTU/hr | 0.60 therm | 0.66 gal | 2.8 lb |
| 75,000 BTU/hr | 0.75 therm | 0.82 gal | 3.5 lb |
| 90,000 BTU/hr | 0.90 therm | 0.98 gal | 4.2 lb |
| 120,000 BTU/hr | 1.20 therm | 1.31 gal | 5.6 lb |
Rounded to two decimals. A set on a manual safety pilot also burns a small standing pilot flame between fires — trivial per hour, but it runs 24/7 unless you shut it off out of season.
The math, so you can check us
Three constants do all the work, and none of them are our opinion:
Where to find your rate: it is on the supply line of your gas bill, usually as $/therm or $/CCF for natural gas and $/gallon on a propane delivery ticket. Use your own number. Anyone quoting you a single national price is quoting you a number that is wrong in most of the country.
Same logs, very different bill
The set does not care which fuel it burns — but your wallet will, because the two are priced in different units on different markets. Propane is typically the more expensive way to run the same flame, and it is also the fuel most likely to move sharply from one delivery to the next. If you have both options at the house, run the calculator twice with each rate before you choose an orifice.
Two practical notes that catch people out. First, the fuel is not interchangeable after the fact — the burner is drilled and configured for one or the other, so pick correctly at order time. Every set we sell is ordered as natural gas or propane, and our team confirms it with you before it ships. Second, propane at altitude can require derating; if you are well above sea level, tell us before you order.
Not sure which fuel is at your fireplace? Look at the shutoff valve and the meter: a gas meter on the outside wall means natural gas; a tank in the yard or a cylinder means propane. If you are still unsure, call us — a 30-second description settles it, and getting it wrong is an expensive mistake to unwind.
Vent type doesn't change what you burn — it changes what you keep
This is the part most articles get backwards. Per BTU, both types cost exactly the same to run. A 60,000 BTU/hr vented set and a 60,000 BTU/hr vent-free set burn identical fuel per hour. What differs is where that heat ends up, and that is a comfort question rather than a fuel-cost question:
- Vented runs with the damper open, so most of the heat goes up the chimney along with some already-heated room air. You are paying for the fire, not for the warmth. Vented sets are also commonly rated at higher BTU inputs, so the hourly fuel figure tends to be higher on both counts.
- Vent-free runs with the damper closed and keeps essentially all of its heat in the room, which makes it the cheaper source of actual warmth per dollar — where local code allows it. It also has a hard BTU ceiling tied to room volume, so it cannot be sized as large.
If your goal is a fire to look at, buy vented and stop thinking about heat. If your goal is a room that gets warmer, read vented vs vent-free gas logs first — including where vent-free is prohibited (Minnesota, Wisconsin and New York City), where its sale is barred (California, with a written exception for decorative sets in a vented fireplace) and where it is allowed with conditions (Massachusetts: fire-department permit, CO detector, 40,000 BTU/hr limit).
Gas logs vs burning real wood
Firewood prices are local and seasonal, so we will not pretend to know yours — get a cord price from a supplier near you and compare it against your calculator result. What we can tell you is what the two costs are actually made of, because the fuel line is only part of the picture:
| Gas logs | Real wood | |
|---|---|---|
| Fuel cost | Predictable: BTU rating × your utility rate, calculable to the cent | Local, seasonal, and it varies with species and moisture content |
| Time cost | Zero. A switch, a remote or a match | Hauling, stacking, kindling, tending, waiting for it to die down |
| Cleanup | None. No ash, no soot on the mantel | Ash removal every few fires |
| Chimney service | Annual inspection still sensible | Sweeping driven by creosote build-up |
| Spontaneity | Fire in ten seconds, any evening | A project — which is why most wood fireplaces get used a handful of times a year |
The honest summary: wood is often cheaper per BTU and almost always more expensive per evening once your own time counts for anything. Gas logs win on use — a fireplace you light 60 nights a year beats a cheaper one you light six times.
How to cut what your fireplace costs you
Frequently asked questions
Are gas logs expensive to run?
How much gas does a gas log set use per hour?
Is propane or natural gas cheaper for gas logs?
Do vented gas logs cost more to run than vent-free?
Does a standing pilot light cost much?
Where do I find my set's BTU rating?
Now pick the set that fits
You know the running cost. The next question is which set actually fits your firebox — width, depth, vent type and fuel. Answer a few questions and the sizing tool narrows it down, or talk it through with a specialist who does this all day.
Prefer a human? Call (949) 619-7824 — we'll match a set to your fireplace, your fuel and your local code together.