How this calculator works
Gas meters count volume, but you pay for heat. This converts what the meter read (CCF, MCF or cubic meters) into therms with the factor printed on your bill, then prices it the way a utility does: a supply charge and a delivery charge per therm, a fixed customer charge, and taxes on top.
- Therms = CCF × therm factor (MCF × 10 × factor; cubic meters × 35.3147 ÷ 100 × factor).
- Usage charges = therms × supply rate + therms × delivery rate.
- Bill = (usage charges + customer charge) × (1 + tax %).
Worked example
With these inputs: gas used 60; measured in CCF (100 cubic feet); therm factor on your bill 1.037; gas supply rate per therm $0.7; delivery / distribution rate per therm $0.45; customer charge $15; taxes and surcharges 5%.
The result is estimated gas bill $90.88, with therms billed 62.22 therms and gas supply charge $43.55. Supply rates change monthly with the market, and some utilities bill in tiers or add a separate weather or fuel adjustment. Use the rates from your latest bill for the closest estimate.
Why your bill converts CCF to therms
The meter measures volume, but gas is sold by the heat it delivers. One therm is 100,000 Btu. Pipeline gas in the US averages roughly 1,037 Btu per cubic foot (EIA), so 100 cubic feet (one CCF) is about 1.037 therms. The exact figure changes a little each month with the gas mix, which is why your bill prints a "therm factor", "Btu factor" or "therm multiplier". Enter that number for an exact match.
If your utility already shows usage in therms, choose Therms and the factor is ignored. Canadian and many international bills meter in cubic meters; 1 cubic meter is 35.31 cubic feet.
Supply, delivery and the customer charge
Most gas bills split into a supply (commodity) charge for the gas itself, a delivery or distribution charge for the pipes, and a fixed customer charge you pay even in a month with no use. In the example the supply charge is $43.55, delivery $28.00 and the customer charge $15.00. In a 20-therm summer month the same rates give $39.90, so the fixed charge is more than a third of the bill; in a 150-therm cold month the bill is $196.88.
Because winter bills can be several times the summer ones, many utilities offer budget billing, which spreads the yearly total into equal monthly payments. Add the gas bill to your utility bill estimate and the yearly expenses calculator to see what it costs over a whole year.
Sources
Frequently asked questions
How do I calculate my gas bill from CCF?
Multiply the CCF by the therm factor on your bill to get therms, multiply the therms by the supply and delivery rates, add the fixed customer charge, then add tax. 60 CCF × 1.037 = 62.22 therms; at $0.70 + $0.45 a therm, $15 fixed and 5% tax, that's $90.88.
How many therms are in a CCF?
About 1.037, because US natural gas averages roughly 1,037 Btu per cubic foot and a therm is 100,000 Btu. Your bill prints the exact factor for the month.
What is a therm of natural gas?
A unit of heat equal to 100,000 Btu. Utilities bill in therms so you pay for the energy in the gas, not just its volume.
Why is my gas bill so high in winter?
Heating is by far the largest use of gas in most homes, so use can jump from 20 therms in summer to 100–150 in a cold month. At the example rates that's $39.90 versus $136.50 to $196.88.
What is the customer charge on a gas bill?
A fixed monthly fee for being connected to the gas system, charged whether or not you use any gas. It covers the meter, billing and service costs.