How Much Does It Cost to Run a Gas Furnace? (With Calculator)

How much does it cost to run a gas furnace?

Most homeowners pay $5.50 to $8.00 per day to run a natural gas furnace during average winter days. But the range for gas furnace operating cost is wide because furnaces vary in size from about 40,000 to 140,000 BTU with efficiencies from 80% to 99%. And your climate is a big factor too.

This Pick HVAC gas furnace cost calculator & guide gives you accurate information about the cost to run a gas furnace based on average run times and average gas prices in your state.

Our Chart gives quick answers based on furnace size.

Pick HVAC Natural Gas Calculator – Cost to Run Gas Furnace per Hour or Longer

Here is the calculator. If you know the needed data, plug it in. Otherwise, below the natural gas furnace operating cost calculator are a handy Chart based on common furnace sizes plus step-by-step directions.

Gas Furnace Running Cost Calculator

How to Use the Cost to Run a Gas Furnace Calculator

Here is what you need to know:

1. Furnace BTU Input – How big is your furnace? You want the number of BTUs it creates when running on high fire – full blast, in other words.

Where can I find furnace BTUs? That’s a common question. See your Owner’s Manual, which should list it. If you don’t have the manual, search the furnace brand and model number online, and you can find the information.

Another option is to use the metal plate inside the furnace cabinet. It will list model number along with serial number and other information. The model number will be a series of numbers and letters, but look for a 60, 80, 90, 100, 120 or similar in the number that indicates the BTU input. For example, the Trane XC95m furnace model TUHMC100ACV4VB is a furnace with 100,000 BTU input.

Type in the number of BTUs or use the Up/Down arrows to select the right amount.

2. Enter your State

It’s amazing how much the cost of natural gas varies across the country.

Choose/click the Your State box, and scroll down and select your state. Watch the Gas Price box change when you do.

3. Gas Price – Change If Needed

We keep track of natural gas price per therm across the United States.

However, even within states, the cost can vary. So, if you want the most precise data, find it on your gas invoice. If it is listed in price per 1,000 cubic feet (Thousand Cubic Feet), then see the conversion below. In short, 1,000 cubic feet = is 9.92 therms, or rounded to 10 therms.

Tip: If your cost is different that what appears in the box, simply select the box and enter your cost.

4. Get your Answer

Your Cost to run gas furnace per hour will appear.

Now, keep in mind that the cost shown is for a cold winter day. If the weather is milder or bitter cold, the cost will go down or rise accordingly based on the length of time the furnace runs.

Quick Chart – Cost to Run Gas Furnace per Hour / Day / Week

This handy chart gives averages for common furnace sizes from 30K to 100K BTUs. It is based on an average winter day when the furnace runs about 35 minutes per hour.

Feel free to time your furnace – in fact, we recommend that you do. But it gets complicated. A single-stage furnace runs at 100% capacity all the time, so cycles tend to be shorter and more frequent.

Two-stage and variable capacity furnaces run between 40% and 65% capacity most of the time, so cycles are longer but are burning less natural gas each minute.

Still, our Gas Furnace Running Cost Chart is a good place to find the average for a furnace or your size.

Converting Therms to 1,000 Cubic Feet

This section might help you use our Cost to Run Gas Furnace Calculator and the Chart above.

Is the price of gas on your gas bill listed in cost per 1,000 cubic feet (aka per Thousand Cubic feet)?

Key: These conversions will help you put the right numbers into the calculator.

  • 1 Therm = 100 cubic feet
  • 10 Therms = 1,000 cubic feet

Simply reverse the equations if your price is given in cost per 1,000 cubic feet, which is often written out as per Thousand Cubic Feet.

  • 1,000 cubic feet = 10 Therms

If the invoice from your gas provider/utility company lists gas price in therms, then use the conversions above.

For example, one Atlanta, GA gas provider lists its cost in therms.

Here’s how you would convert that to Thousand Cubic Feet in order to use our Chart:

  • 1,000 Cubic Feet = 10 Therms and
  • 10 Therms = 1,000 Cubic Feet

Multiplying the cost per therm, here is the answer:

10 x $0.419 = $4.19

So, given a cost of $0.419 per therm, we easily convert that to $4.19 per 1,000 cubic feet, aka $4.19 per Thousand Cubic Feet.

What’s MMBtu? It stands for million BTUs and 1 MMBtu = 10 therms. This is mentioned because the wholesale cost of natural gas is listed in MMBtu. That’s not the cost to consumers, by the way, so you shouldn’t use it to try to determine your cost. See your Invoice for precise price information.

Did you Know? Prices are Rising

With current inflation and with less domestic gas production, costs are trending higher.

This page from the Energy Information Agency shows the 6-month history for the US and for each state. It might help you project and budget for your upcoming natural gas costs.

Written by

Rene has worked 10 years in the HVAC field and now is the Senior Comfort Specialist for PICKHVAC. He holds an HVAC associate degree and EPA & R-410A Certifications.

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