How Much Does It Cost To Run A Gas Fireplace? (Per Hour, Day, Month)

“Is a gas fireplace expensive to run?”

Before buying a gas fireplace, it’s smart to ask just that question. All heating units – furnaces, heaters, and fireplaces – burn natural gas, propane or electricity to generate heating output. We will look into how much does it cost to run a gas fireplace per hour, per day, and per month.

How much gas does a gas fireplace use?

A standard 20,000 BTU gas fireplace will use about 20 cubic feet of natural gas per hour. Given that price of natural gas is about $1.09 per 100 cubic feet, running a standard-sized gas fireplace will cost about $0.22/hour at 100% heating output.

In short: Gas fireplaces are quite inexpensive to run. This is primarily due to the low cost of natural gas and propane. On average, 100,000 BTU worth of heat costs $1.09 if you use natural gas and $3.87 if you use electricityGas fireplaces have about 3 times lower running costs than electric fireplaces (for the same heating output).

natural gas or propane fireplace running costs
Gas fireplaces are pretty inexpensive to run. That’s primarily because the price of natural gas and propane are very (about $1.09 per 100,000 BTU) low compared to the price of electricity (about $3.87 per 100,000 BTU).

Now, it’s important to understand that the exact running cost of gas fireplaces depends on several factors. These include per day usage, average percentage heating output (not always 100%), gas fireplace energy efficiency, and so on (we’ll go a bit into details on these key factors later on).

We can, however, very accurately determine how much does it cost to run a gas fireplace per hour (running at 100% specified heating output). Here are the maximum costs of running 10,000 BTU to 40,000 BTU gas fireplaces per hour (at natural gas prices of $1.09 per therm):

  • Small 10,000 BTU gas fireplace costs $0.15 per hour to run. That’s $108 per month (absolute max. cost, gas fireplace running 24/7).
  • Standard 20,000 BTU gas fireplace costs $0.29 per hour to run. That’s $208.8 per month (absolute max. cost, gas fireplace running 24/7).
  • Big 40,000 BTU gas fireplaces cost $0.58 per hour to run. That’s $417.6 per month (absolute max. cost, gas fireplace running 24/7).

You don’t run a gas fireplace at 100% heating output 24/7, however. Below we’ll see how much these running a gas fireplace per month costs are reduced in practice.

In general, we need to include only 2 two factors to adequately calculate how much it costs to run a gas fireplace at 100% heating output. (You can figure out how much will the gas for your gas fireplace cost with the calculator below)

These are:

  1. Size of the gas fireplace. Here we talk about rated BTU input. Gas fireplaces can have anywhere from 8,000 BTU to 40,000 BTU rated input. Below you will also find instructions on how to adequately size a gas fireplace for certain square footage (from 100 – 2,000 sq ft), if you need help figuring out how many BTUs you would need.
  2. Price of gas. The price of natural gas and propane varies state by state and even month by month. It is expressed as ‘price per therm’. 1 therm is equal to 100,000 BTUs of energy. US national average price of natural gas is $1.09 per therm (Natural Gas Price by EIA here).

Note: The calculation will give you the absolute maximum cost of running a gas fireplace per hour. It presumes that the gas fireplace operates at 100% capacity. In practice, when a certain temperature is reached (most often thermostat temperature setting), the output will fall significantly and so will the running costs.

How Much Does It Cost To Run A Gas Fireplace Per Hour: Calculator


*In calculation, we presume that the energy efficiency of a gas fireplace is 75% (75 AFUE rating) and that a gas fireplace runs at 100% heating capacity for the whole hour.

Let’s illustrate how you can use this gas fireplace running costs calculator to determine the gas expenditure of natural gas and propane fireplaces in dollar amounts:

How To Calculate Gas Fireplace Running Costs

The simplest way is to use the calculator above. However, let’s first do it by hand; in this way, you can see the logic behind how calculating the gas fireplace running costs looks like.

We’ll take a standard-sized 20,000 BTU gas fireplace as an example. If such a gas fireplace would have 100% efficiency, it would require 20,000 BTU of gas per hour to run at 100% output.

However, gas fireplaces can have anywhere from 60 to 90% energy efficiency. If you’re interested, you can check the AFUE rating that determines the energy efficiency of gas furnaces here. For this example, we will make the same assumption that is made in the calculator above: 75% gas efficiency.

Now we have a 75% energy-efficient gas-powered fireplace with 20,000 BTU heating output. We need to calculate how much gas we need to generate that output.

At 100% energy efficiency, we would need 20,000 BTU. But because we have a realistic 75% efficient fireplace, we’ll need more. How much more? Let’s calculate:

20,000 BTU / 0.75 = 26,667 BTU

We’ll need 26,667 BTU worth of gas. Gas prices are price per therm; 1 therm is equal to 100,000 BTU and that costs, an average, of $1.09. Well, if 100,000 BTU costs $1.09, how much does 26,667 BTU costs? Here’s the calculation:

26,667 BTU * ($1.09 / 100,000 BTU) = $0.29

That means that running such a gas-powered fireplace will cost:

  • $0.29 per hour.
  • $6.96 per day (24h).
  • $48.72 per week (168h).
  • $208.8o per month (720h).

Of course, that is only if you run it all the time at 100% heating output.

Let’s use the gas fireplace cost calculator above to confirm this result:

how much does it cost to run a gas fireplace per hour

We can see that we get the same result.

Obviously, there are many factors that affect how much any type of gas fireplace will cost to run. This includes:

  • Indoor gas fireplaces.
  • Gas fireplace inserts.
  • Outdoor gas fireplaces.
  • See-through gas fireplaces.

Two primary factors are specified BTU output and price of natural gas (or propane) per therm. Based on these, we can accurately determine the costs per running hour. However, to get an idea of how much does gas for gas fireplace costs if we run it per day, week, or month, we need to take other things into consideration.

Here are the 4 main secondary factors that will illustrate if the gas fireplace is indeed expensive to run:

#1 How Many Hours Per Day Do You Run A Gas-Powered Fireplace?

Nobody runs a gas fireplace 24 hours per day. If you would do that with a 20,000 BTU 75% energy-efficiency fireplace, you would spend about $6.96 per day (given $1.09 per therm natural gas price).

You will likely pay a lot less because you run it only 1, 2, 4, 8 hours per day, and so on.

Here’s how much you’re likely to spend if you run a gas fireplace a limited number of hours per day (realistic price):

Daily Running Hours (Hours/Day) Small Gas Fireplace (10,000 BTU) Standard Gas Fireplace (20,000 BTU) Big Gas Fireplace (40,000 BTU)
1 hour $0.15/day $0.29/day $0.58/day
2 hours $0.30/day $0.58/day $1.16/day
4 hours $0.60/day $1.16/day $2.32/day
8 hours $1.20/day $2.32/day $3.48/day
12 hours $1.80/day $3.48/day $6.96/day

In short, if you run a standard indoor gas fireplace 4 hours per day, you will spend about $1.16 per day on natural gas. That is only if you run it at 100% heating output.

#2 You’re Not Running The Unit At 100% At All Times

When a certain temperature is reached (usually thermostat temperature), the gas fireplace won’t produce 100% heating output. The output should only be used to maintain the set temperature. In actuality, you’re matching the output with heat loss. That can reduce the heating output by as much as 90% of the total capacity.

Example: Your indoor temperature is 62°F and you set 72°F on the thermostat. A 20,000 BTU gas fireplace will produce 20,000 BTU (100% heating output) unit 72°F is reached. After that, the output will be heavily reduced; even down to 10% of output or 2,000 BTU.

How much the output of the gas fireplace is reduced is mainly influenced by heat loss. More insulated homes/rooms will lose less heat, and therefore the gas fireplace will have to run at the lower heating output to maintain the 72°F temperature.

Heat loss also depends on climate:

  • Cold climate (North USA): Higher heat loss, hence higher stationary temperature gas fireplace costs.
  • Warm climate (South USA): Lower heat loss, hence lower stationary temperature gas fireplace costs.

#3 Energy Efficiency Of Gas Fireplaces (60% – 90%)

It’s important to take energy efficiency into account. Electric fireplaces are about 99% efficient; almost all electricity goes to heat.

Gas fireplaces, however, have lower efficiency. More inefficient ones run on 60% efficiency and the most energy-efficient gas fireplaces run on 90% efficiency. In the calculator above, we presume 75% efficiency; a rough average.

The logic here is quite clear: More efficient gas fireplaces will require less gas to produce the same heating output. Less gas means fewer dollars and lower natural gas bills.

To illustrate, we can compare a running cost of 20,000 BTU gas fireplace. To produce 20,000 BTU of heating output:

  • 60% efficient unit will draw $0.36 worth of natural gas.
  • 70% efficient unit will draw $0.31 worth of natural gas.
  • 80% efficient unit will draw $0.27 worth of natural gas.
  • 90% efficient unit will draw $0.24 worth of natural gas.

If you want to reduce how much does running a gas fireplace cost, you should obviously invest in a unit with higher energy efficiency (look for 80+ AFUE rating in the specification sheet).

Is Gas Fireplace Expensive To Run? (Final Word)

Not at all. Using natural gas is one of the most inexpensive ways to heat your home. That’s why gas fireplaces, gas fireplace inserts, outdoor gas fireplaces, even gas furnaces are such cost-effective heating options.

Realistically, most gas-powered fireplaces will burn through about $1 worth of natural gas per day. This will yield about 68,807 BTU of heating output.

How much does it cost to run an electric fireplace vs. a gas fireplace is a good comparison that illustrates how inexpensive it is to run a gas fireplace.

If you presume the price of electricity to be $0.1319/kWh and electric fireplace 99% efficiency, and price of natural gas to be $1.09 per therm (100,000 BTU) and gas fireplace 75% efficiency, you get the following result:

  • For every $1, a gas fireplace will produce 68,807 BTU of heating output.
  • For every $1, an electric fireplace will produce 25,612 BTU of heating output.

That means that a gas fireplace is almost three times less expensive to run than an electric fireplace. Admittedly, wall-mounted electric fireplaces (check them here) in most cases only produce about 5,000 BTU/hr of heating output while gas fireplaces produce anywhere from 8,000 BTU to 40,000 BTU output.

However, if you’re using a fireplace just for the ambience (and not for heating purposes), an electric fireplace might be a better choice. Per heating BTU electric fireplace might have a lower cost-performance, but these fireplaces produce only 5,000 BTU, and gas fireplaces produce, on average, 20,000 BTU. In this case, running an electric fireplace is cheaper than running a gas fireplace; but it’s all visual and not heat-based.

If you have any other questions about the calculations, you can pose them in the comments below and we will try our best to help you out.



7 thoughts on “How Much Does It Cost To Run A Gas Fireplace? (Per Hour, Day, Month)”

  1. Thank you for providing such information. This is very generous of you providing such vital information which is very informative.

  2. I found out the hard way that running a standard natural gas in a vented fireplace is indeed expensive. We have used it a lot…like 3-4 hours in the mornings and about the same in the evenings….my gas bill skyrocketed! I thought I was being very careful by turning the gas heat down to 64-65 or completely off when running the gas in the fireplace…then I got my monthly bill and it had tripled!! I had a guy come out from the gas co. to check it…it was fine- no leaks or any other problems –just the usage was the problem. Now, I am so cautious about using it and it’s such a shame because I love a fire when it’s cold. My firelogs do not have a timer, or a thermostat – just an on/off switch and flame control. Wish it did.

    • Hello Edwina, that’s right, if you have a 20,000 BTU gas fireplace and run it on 100% all the time, you will get about a $200 heating bill.

  3. What if we have to run a ceiling fan on the lowest setting to keep the big family room warm? Is that still cheaper than running the forced air furnace?
    Sorry, that is we run a gas fireplace with no blower along with the ceiling fan on low to help push the warm air down.

    • Hi Stacy, if you can keep the big family room warm with just a ceiling fan, that is usually much cheaper. Even bigger ceiling fans will run on less than 100 watts (lowest setting). That will consume 0.1 kWh per hour and with the average cost of electricity (about $0.15/kWh), you are spending about 1.5 cents per hour to run a ceiling fan. So, it is much much cheaper to run a ceiling fan than a gas fireplace. Hope this helps.

    • Hi Burt, definitely gas furnace. The efficiency is measured in AFUE values. The modern gas furnaces (especially the 2-stage ones) can extract more than 90% of the energy from nat gas (they have 90+ AFUE values). Fireplaces just can’t compete with gas furnaces as far as efficiency goes.


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