Natural Gas Cost Calculator
A natural gas cost calculator estimates a heating or appliance gas bill from the amount of gas used and the price your utility charges. Residential natural gas is usually billed in therms, where one therm equals 100,000 British thermal units of heat energy. This tool takes the therms used over a period and your rate per therm, then multiplies them to return the cost. Both inputs are editable so you can model a monthly bill, a single appliance, or a full heating season at your own utility tariff. Some utilities bill in hundred cubic feet (CCF) rather than therms; since one CCF of typical natural gas is close to one therm, you can usually enter CCF in place of therms for a rough estimate. Knowing the cost helps you compare heating fuels, judge the value of an efficiency upgrade, or check a surprising winter bill. The US Department of Energy publishes guidance on home heating, fuel comparison and energy efficiency. Both the therms used and the rate appear on your gas bill. Every figure is computed deterministically from the formula shown below, with a worked example that reconciles exactly to the calculator so you can follow each step yourself.
Natural gas cost multiplies the therms used by the rate per therm: cost = therms x rate. Using 80 therms at $1.50 per therm costs $120.00. One therm equals 100,000 BTU of heat.
Natural gas cost formula
Cost = T x R
T = therms of gas used
R = price per therm (dollars)
1 therm = 100,000 BTU
Therms measure the heat energy delivered. Multiplying the therms used by the rate per therm gives the dollar cost on your bill, before any fixed service charges.
Worked example
A household uses 80 therms of natural gas in a month at a rate of $1.50 per therm.
- Therms used = 80
- Rate = $1.50 per therm
- Cost = 80 x 1.50 = $120.00
The gas for the month costs $120.00, before fixed charges. These are the calculator's default inputs, so the result above matches the widget exactly.
Natural Gas Cost Calculator: frequently asked questions
What is a therm?
A therm is a unit of heat energy equal to 100,000 British thermal units (BTU). Residential natural gas is usually billed in therms because it measures the heat the gas provides rather than its volume, which varies with temperature and pressure. One therm is roughly the energy in 100 cubic feet of typical natural gas.
My bill is in CCF, not therms. What do I do?
CCF means hundred cubic feet. For typical pipeline natural gas, one CCF delivers close to one therm of energy, so you can enter CCF in place of therms for an approximate cost. Your utility prints a therm factor on the bill that converts CCF to therms precisely if you want an exact figure.
Does this include fixed charges?
No. This calculator multiplies usage by the per-therm rate to give the usage portion of the bill. Most utilities also add a fixed monthly service or customer charge and sometimes taxes. Add those separately to match your total bill.
How can I lower my gas bill?
Reduce usage by sealing air leaks, adding insulation, lowering the thermostat, and maintaining your furnace so it runs efficiently. The US Department of Energy publishes home energy saving guidance. Switching to a higher-efficiency furnace also lowers the therms needed for the same heat.
Where do I find my gas rate?
Your rate per therm appears on your natural gas bill, sometimes split into a supply (commodity) charge and a delivery charge. Add those components for the full marginal rate per therm. Rates change seasonally and by region, so use your current bill for accuracy.
Official sources
- Home heating fuel comparison and efficiency guidance: US Department of Energy (DOE). As at 25 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 25 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.