Natural Gas Bill Calculator

How to use this calculator

1. Enter your gas usage and unit. Type how much gas you used this billing period, then pick the unit your bill shows: therms or CCF (hundred cubic feet).
2. Enter your price per unit. Copy the rate straight off your bill, then choose whether that price is quoted per therm or per CCF.
3. Add your fixed charge. Enter the flat monthly service or customer charge. Leave it at zero if you do not have one.
4. Add your tax or surcharge. Enter your combined tax or surcharge rate as a percentage, or leave it at zero if none applies.
5. Read your itemized bill. You see the usage charge, fixed charge, subtotal, tax, and estimated total, plus your usage converted to the unit your rate uses.

How it works

This calculator rebuilds your natural gas bill the same way your utility does, using numbers you read off your own statement. You enter your own rate, so the estimate matches your real rate plan no matter which company serves you. The tool does not pull live prices and is not tied to any single utility.

First, you enter how much gas you used and the unit it is measured in. Then you enter the price you pay and whether that price is per therm or per CCF. Bills often measure usage in CCF but charge a rate per therm. When your two units do not match, the tool converts your usage using the U.S. Energy Information Administration average heat content of about 1.037 therms per CCF before doing any math. So 1 CCF of pipeline gas delivers about 1.037 therms, and 1 therm is about 0.9643 CCF. When both units already match, the tool applies no conversion, so the arithmetic is exact for your own rate.

Next the tool works out the three parts of a typical gas bill. The usage charge is your converted usage multiplied by your price per unit. The fixed charge, sometimes called the service, customer, basic, or availability charge, is a flat monthly fee you pay no matter how much gas you burn. The two add up to the subtotal before tax. Finally the tool applies your tax or surcharge percentage to that subtotal and adds it on to produce the estimated total. Every line shows separately so you can compare it against your statement line by line.

The 1.037 therm/CCF factor comes from the U.S. EIA FAQ on Ccf, Mcf, Btu, and therms, which states that 100 cubic feet (1 Ccf) of natural gas equals 103,700 Btu, or 1.037 therms. The EIA British thermal units page confirms that 1 therm equals 100,000 Btu and lists about 1,036 Btu per cubic foot, which corroborates the factor. The California Public Utilities Commission gas glossary independently states that one therm equals 100,000 Btu. The U.S. DOE / ORNL guide to natural gas bills shows real bills use a per-bill factor clustered just above 1.0, so your utility’s exact factor may differ slightly.

Examples

60 therms at $1.20 per therm, $12 service charge, no tax. Your units match, so no conversion happens and billed units stay at 60. The usage charge is 60 times $1.20, or $72.00. Adding the $12 service charge gives a subtotal of $84.00, and with no tax the estimated total is $84.00.

100 CCF used but the rate is per therm at $0.90, $10 fixed charge, 5% tax. Because your usage is in CCF and your rate is per therm, the tool converts 100 CCF to 103.7 therms using the 1.037 factor. The usage charge is 103.7 times $0.90, or $93.33. Adding the $10 fixed charge gives a subtotal of $103.33, the 5% tax adds $5.17, and the estimated total is $108.50.

A worked example like NAGD’s: 25 therms at $1.192 per therm, $6 availability charge, 4% tax. The 25 therms need no conversion, so the usage charge is 25 times $1.192, or $29.80. Adding the $6 availability charge gives a subtotal of $35.80, the 4% tax adds $1.43, and the estimated total is $37.23, matching the published worked figure.

Natural gas units explained: therms, CCF, MCF and BTU

Gas bills mix two kinds of measure. CCF and MCF measure volume, or how much physical gas flowed through your meter. Therms and BTU measure energy, or how much heat that gas can produce. A conversion factor links the two because the energy packed into a cubic foot of gas varies a little by place and time. The table below uses the U.S. average heat content of about 1,037 BTU per cubic foot (U.S. EIA FAQ on Ccf, Mcf, Btu, and therms). One therm equals 100,000 BTU (U.S. EIA, British thermal units).

Unit	What it measures	In BTU	In therms
1 cubic foot (cf)	Volume	1,037 BTU	0.01037 therms
1 CCF (100 cubic feet)	Volume	103,700 BTU	1.037 therms
1 MCF (1,000 cubic feet)	Volume	1,037,000 BTU (1.037 MMBtu)	10.37 therms
1 therm	Energy	100,000 BTU	1 therm

The parts of a natural gas bill

A residential gas statement is built from a few standard line items. Knowing each one tells you which figure to type into which field above.

Fixed customer charge

A flat monthly fee for the connection itself, covering billing, meter reading, and upkeep of the line to your home. You pay it even in a month you burn no gas (U.S. DOE / ORNL guide to natural gas bills). It can appear as a service charge, basic charge, customer charge, or availability charge. Enter it in the fixed monthly service charge field.

Usage or commodity charge

The cost of the gas you actually used: your consumption multiplied by the price per unit (U.S. DOE / ORNL guide to natural gas bills). This maps to the usage and price fields, and the calculator returns it as the usage charge.

Delivery or distribution charge

The cost of moving gas through the pipes to your meter, often listed separately from the gas itself (U.S. DOE / ORNL guide to natural gas bills). If your utility splits supply and delivery, add the two rates together and enter the combined figure as your price per unit.

Taxes and surcharges

Sales tax, utility tax, or local surcharges applied as a percentage of the subtotal. Enter your combined rate in the tax field, or leave it at zero if none applies. The calculator returns it as the tax line. To find your usage figures in the first place, read the meter using the steps your utility documents (U.S. DOE Energy Saver, how to read gas meters).

What makes your gas bill go up or down

A gas bill can swing a lot from one month to the next, and three levers explain almost all of it. Sorting your bill into these three buckets tells you whether a spike came from the weather, the market, or something fixed you cannot change.

The first lever is how much gas you used. Heating demand drives most of it, so a cold month sends usage up while a mild month brings it down (U.S. EIA, factors affecting natural gas prices). The second lever is the price per therm or CCF, which moves with supply, how much gas is in storage, and seasonal demand across the market (U.S. EIA, factors affecting natural gas prices). The third lever is your fixed charge and taxes, which stay roughly steady from month to month.

The hardest months happen when the first two levers move together. A cold spell raises how much gas you burn at the same time it pushes up the market price, so both halves of the usage charge climb at once and the total jumps more than either change alone would suggest.

Use the calculator to tell the levers apart. Plug in last month’s figures, then this month’s, and compare the usage charge against the fixed charge.

• Usage went up but the rate held steady: the swing is volume, usually weather and heating demand.
• The rate per unit climbed: the swing is market price, driven by supply and seasonal demand.
• Only the fixed charge and tax changed: the swing is structural, not something your thermostat controls.

How to read your gas meter and verify your bill

You can check a bill yourself by reading the meter and rerunning the numbers here. Follow these steps.

• Read the dials left to right. A dial gas meter reads in the opposite direction from an electric meter, so work across the dials from left to right and write down each number (U.S. DOE Energy Saver, how to read gas meters).
• Subtract the last reading. Take this period’s reading and subtract the previous period’s reading to get the cubic feet of gas you used (U.S. DOE Energy Saver, how to read gas meters).
• Note the unit your utility bills in. Check whether your statement charges in CCF, MCF, or therms, since that decides which unit to pick above. One CCF is 100 cubic feet and 1 MCF is 1,000 cubic feet (U.S. EIA FAQ on Ccf, Mcf, Btu, and therms).
• Run your figures and compare. Enter your usage and your bill’s rate into the calculator, then check each line, the usage charge, fixed charge, subtotal, and tax, against your statement.

What the data says

If you have ever opened a cold-month bill that nearly doubled from December to January, you are not imagining it. Winter is when gas bills bite hardest, and seeing the jump coming is half the battle. This calculator helps you do that, and a little national context shows why a deep-winter estimate can look so steep.

Start with the season as a whole. Federal forecasters expect the typical US home that heats with natural gas to spend about $642 across the winter heating season, November 2025 through March 2026, roughly 1 percent below the prior winter (EIA Winter Fuels Outlook). A single month is only one slice of that total, so a $150 bill in January is part of a much larger seasonal arc, not a sign that your meter has gone haywire.

That seasonal weight lands harder on some households than others. Energy-assistance officials warn that even modest-looking increases can strain a tight budget.

“These increases may not sound dramatic to higher-income households, but for families already struggling, they are devastating.”

Mark Wolfe, Executive Director, National Energy Assistance Directors Association.

The season also does not spread its cost evenly. The same EIA forecast splits that winter total across the months, from about $112 in November up to roughly $146 in January before easing through the spring (EIA Winter Fuels Outlook). That curve is why a midwinter bill can run far higher than a fall one even when your habits have not changed.

Month	Forecast household gas heating spend
November	$112
December	$142
January	$146
February	$127
March	$115
Winter total	about $642

You are not alone in watching this number. Natural gas was the main space-heating fuel in about 47 percent of US homes in 2024, just ahead of electricity at 42 percent (EIA Today in Energy (Census 2024 data)). So most readers running this estimate share the same seasonal cost pattern, and the same surprises.

A few of those surprises come up again and again:

• People often get blindsided by a midwinter spike, feeling the bill jumped far more than their usage actually did.
• A common mistake is reading only the gas part of the bill and ignoring delivery, then being startled when the delivery line is larger than the cost of the gas itself.
• People often assume the meter is broken before benchmarking, when the real fix is comparing this bill against their own past usage.

What this tool does that others don’t

• You enter your own rate, so it works for any utility. Most top calculators lock you into one company’s published rates, so a customer on any other utility cannot get an accurate number. This tool lets you type the rate, fixed charge, and tax straight off your own bill, for any utility and any country.
• It handles the therm-versus-CCF mismatch for you. Bills often quote usage in CCF while rates are per therm. No competitor applies the 1.037 therm/CCF conversion automatically, leaving you to do the math by hand. This tool converts your usage before applying your rate.
• It itemizes every line. Many calculators give a single total. This tool breaks out the usage charge, the fixed charge, the subtotal, and the tax separately, so you can see what drives your bill and check it against your statement.

Frequently asked questions

How do I calculate my natural gas bill?

Multiply your usage by your price per unit to get the energy charge, add your fixed monthly service charge to get the subtotal, then add any tax or surcharge. This calculator does all three steps for you and shows each part separately.

What is the difference between therms and CCF?

CCF measures the volume of gas you used (one CCF is 100 cubic feet), while a therm measures the energy content (100,000 BTU). They are not identical because the energy in a cubic foot of gas varies slightly, which is why a conversion factor is needed.

How many therms are in one CCF?

On average about 1.037 therms per CCF, based on the U.S. Energy Information Administration figure that natural gas delivered to consumers contains roughly 1,037 BTU per cubic foot. Your utility prints the exact factor it uses on your bill, and it is usually close to 1.0.

My bill shows usage in CCF but the rate is per therm. What do I do?

Pick CCF as your usage unit and therm as your price unit. The calculator automatically converts your CCF usage to therms using the 1.037 factor before applying your rate, so you do not have to do the conversion yourself.

What is the fixed or customer charge?

It is a flat monthly fee your utility charges to cover meter reading, billing, and maintaining the connection to your home. You pay it even if you use no gas at all. It may appear as a service charge, basic charge, customer charge, or availability charge.

Where do I find my price per therm or per CCF?

Look on your gas bill for the supply or commodity rate plus any delivery or distribution rate; together they make up your price per unit. Add them if your utility lists them separately, and enter the combined figure here.

Does this calculator use current gas prices?

No. It uses only the rate you enter, so it works for any utility, country, or billing period. Because gas prices change with the season and the market, always copy the figures from your most recent bill for the most accurate estimate.

Why is my actual bill different from this estimate?

Real bills can include tiered or seasonal rates, separate supply and delivery line items, riders, credits, budget billing, or a conversion factor that differs slightly from 1.037. This tool uses a single flat rate, so treat the result as a close estimate, not an exact invoice.

Is tax really added to natural gas bills?

In many places yes. Sales tax, utility tax, gross receipts tax, or local surcharges may apply, often as a percentage of the subtotal. Enter your combined tax or surcharge rate, or leave it at zero if none applies.

How can I lower my natural gas bill?

Lowering thermostat settings, sealing drafts, adding insulation, servicing your furnace, and using a programmable thermostat all cut usage. Because the fixed service charge does not change, reducing how many therms you burn is the main lever you control.

Sources

• U.S. EIA FAQ: What are Ccf, Mcf, Btu, and therms? How do I convert natural gas prices…. States that 100 cubic feet (1 Ccf) of natural gas equals 103,700 Btu, or 1.037 therms, and that dividing $/Ccf by 1.037 gives $/therm.
• U.S. EIA, British thermal units (Btu), Energy Explained. States 1 therm equals 100,000 Btu and lists about 1,036 Btu per cubic foot, corroborating both the therm definition and the CCF factor.
• California Public Utilities Commission, Gas Glossary. Independent state utilities commission source confirming one therm equals 100,000 BTU.
• U.S. DOE / ORNL, Understanding Your Utility Bills: Natural Gas (ORNL/SPR-2021/1832). Documents that utilities convert measured CCF volume to therms using a per-bill heat-content factor near 1.0, confirming real factors cluster around the EIA 1.037 average.