This natural gas converter exists to solve one problem that a generic energy converter cannot touch: natural gas is metered by volume and sold by energy, and the bridge between the two is a heating value that changes depending on where you live and what is in the pipeline. Convert a Ccf to a therm with a fixed factor and you will be wrong by a few per cent, which matters when you are checking a bill or comparing two supply offers.
Arb Digital publishes this as part of a free tools library used by people who need to check a number rather than take it on trust. The tool asks for your heating value as an input rather than baking one in, because the correct value is printed on your own statement and nobody else's number is right for your meter.
What This Natural Gas Converter Does
It converts a quantity of natural gas between ten units that fall into two families. The volume units are cubic feet, hundred cubic feet (Ccf), thousand cubic feet (Mcf) and cubic metres. The energy units are BTU, therms, dekatherms (also written MMBtu), kilowatt-hours, megajoules and gigajoules. Crossing between the two families requires the heating value; converting inside a family does not.
It also prices the result. Enter what you actually pay and the unit that price is quoted in, and the tool converts your quantity into that unit before multiplying, so a price quoted per Mcf and a quantity entered in cubic metres still produce a sensible number.
The boundary with the site's other converters is worth stating. The energy converter handles joules, calories, kilowatt-hours and BTU as pure energy units, and it cannot turn a cubic foot into a therm because that conversion is not a fixed ratio. The volume converter handles cubic feet and cubic metres as pure volume. This page is the one that bridges the two families, and the heating value input is the entire reason it can.
How to Use It
- Enter the amount and the unit you have. Meter readings are usually in Ccf or cubic metres; bills are usually in therms or dekatherms.
- Choose what you want it in. Any unit in either family is available in both directions.
- Set the heating value from your bill. Look for BTU factor, therm factor, heat content or energy content. If your bill shows therms and Ccf side by side, divide therms by Ccf and multiply by 1,000 to recover the BTU per cubic foot.
- Enter your price and the unit it is quoted in. Use the commodity rate if you want the gas cost alone, or the all-in rate if you want the delivered cost.
- Read the result and the supporting figures. The four boxes always show therms, cubic feet, kilowatt-hours and cost regardless of which units you selected.
The Formula: How the Conversion Works
Everything routes through BTU. A therm is defined as exactly 100,000 BTU and a dekatherm as exactly 1,000,000 BTU, so those two are pure arithmetic. A cubic foot of gas carries whatever energy the heating value says it carries, which is where your bill's number enters:
Energy in BTU = volume in cubic feet × heating value in BTU per cubic foot
Worked example, which is also the default on this page. Take 1 Mcf — one thousand cubic feet — at a heating value of 1,037 BTU per cubic foot. That is 1,000 × 1,037 = 1,037,000 BTU. Divide by 100,000 and you get 10.37 therms. The US Energy Information Administration guidance on converting natural gas prices publishes exactly this conversion, noting that 1,000 cubic feet equals 10.37 therms at the 2025 US average heat content, and that 100 cubic feet equals 1.037 therms. Divide the same 1,037,000 BTU by 3,412.14 — the BTU per kilowatt-hour factor listed in the EIA energy units and calculators reference — and you get 303.9 kilowatt-hours, which is the same energy expressed the way an electricity bill would state it.
Cubic metres convert to cubic feet by the exact factor 35.3146667, since a foot is exactly 0.3048 metres. So one cubic metre at 1,037 BTU per cubic foot carries about 36,621 BTU, or roughly 38.6 megajoules — which is why metric gas bills often quote a calorific value somewhere between 37 and 39 megajoules per cubic metre.
Why the Heating Value Is Not a Constant
Pipeline natural gas is mostly methane, but it also contains ethane, propane, butane, nitrogen and carbon dioxide in varying proportions. The hydrocarbons raise the energy content and the inert gases lower it. Because gas from different fields and different processing plants blends in the transmission system, the mixture arriving at your meter is not the same as the mixture arriving at a meter three states away, and it is not the same in January as it was in July.
The size of the variation is not trivial. The EIA heat content of natural gas delivered to consumers series shows annual averages spanning roughly 917 to 1,096 BTU per cubic foot across US states in recent years — a spread of about 19 per cent between the extremes. If you convert Ccf to therms using a flat 1.00 factor when your utility's actual factor is 1.05, every bill you check will look five per cent cheaper than it is.
This is also why utilities bill in therms rather than in volume where they can. The meter measures volume because that is what a meter can physically do, and the utility then multiplies by a periodically measured heat content to arrive at the energy you were actually delivered. Your bill should show both numbers. If it only shows one, the conversion factor is almost always disclosed somewhere in the rate schedule.
Ccf, Mcf, Therms and Dekatherms: Decoding the Vocabulary
The unit names in this industry are a trap for anyone reading them for the first time, because the abbreviations use Roman numerals in a way nothing else does. C means one hundred and M means one thousand, so a Ccf is one hundred cubic feet and an Mcf is one thousand cubic feet. That M is not the metric mega prefix — an MMcf, confusingly, is a thousand thousand, which is a million cubic feet.
On the energy side, a therm is 100,000 BTU and a dekatherm is ten therms, or one million BTU. Because a million BTU is also written MMBtu, dekatherm and MMBtu are the same quantity and are used interchangeably in wholesale markets. Residential bills tend to use therms or Ccf; commercial and wholesale contracts tend to use dekatherms or MMBtu.
The practical consequence is that "gas is four dollars" is a meaningless statement without a unit. Four dollars per dekatherm is roughly forty cents per therm. Four dollars per therm is ten times that. When you are comparing two supply offers, convert both to the same unit here before you look at the numbers, because suppliers do not all quote the same way.
Comparing Gas and Electricity Honestly
Converting a therm to kilowatt-hours is easy, and it is also the single most common way people mislead themselves about heating costs. One therm equals 29.3 kilowatt-hours of energy content, so if gas costs a dollar a therm and electricity costs fifteen cents a kilowatt-hour, gas looks about four times cheaper per unit of energy. That comparison is only valid if both appliances turn energy into heat with the same efficiency, and they do not.
A gas furnace converts a stated fraction of its input energy into delivered heat — the rest goes up the flue. Resistance electric heating converts essentially all of the electricity into heat at the point of use. A heat pump does something different again: it moves heat rather than making it, and can deliver more heat energy than the electrical energy it consumes. To compare fairly you have to divide the fuel cost by the appliance efficiency, and the efficiency figures have to come from the appliance nameplates, not from a general rule.
Use this page to get both fuels onto the same energy unit, then apply your own equipment's efficiency figures. The electricity bill calculator covers the kilowatt-hour side of the same question, the furnace size calculator deals with sizing rather than fuel cost, and the heat loss calculator estimates how much heat a building needs in the first place.
Reading a Gas Bill Against Your Own Meter
A residential gas meter counts volume, usually in hundreds of cubic feet in North America and in cubic metres elsewhere. If you want to check a bill, read the meter at the start and end of a period, take the difference, and convert it here using the heating value from that same bill. The result should match the billed therms within rounding.
Two things can legitimately make it not match. Some meters record in cubic feet rather than Ccf, so a reading difference of 25 might mean 25 Ccf or 25 cf depending on the dial — a factor of a hundred. And some utilities apply a pressure correction factor, because gas delivered above standard pressure occupies less volume for the same number of molecules; that factor appears on the bill as a multiplier close to 1.0. Apply the pressure factor to the volume before converting, and the arithmetic should reconcile.
If it still does not reconcile, the disagreement is with the utility rather than with the maths, and the bill's own customer service route is the place for it. This page computes; it does not audit.
Arb Digital's free tools library covers the budgeting, demand and measurement maths behind growing a services business online, and our team is happy to talk through anything the tools cannot answer.
Browse Free Tools Talk to Arb DigitalCommon Mistakes to Avoid
- Treating a Ccf as exactly one therm — it is only one therm when the heating value is exactly 1,000 BTU per cubic foot, which it almost never is.
- Reading the M in Mcf as mega — it means one thousand, so an Mcf is a thousand cubic feet, not a million.
- Comparing gas and electricity on energy alone — the appliance efficiency has to be applied to both sides before the comparison means anything.
- Using a national average heating value — the number on your own bill is the only one that reconciles with your own meter.
- Ignoring the pressure correction factor — where a utility applies one, the raw meter difference is not the billed volume.
Related Free Tools From Arb Digital
Use the energy converter for pure energy unit conversions, the volume converter for volume alone, the electricity bill calculator for the kilowatt-hour side of a utility bill, the AC BTU calculator for cooling capacity in BTU per hour, and the fuel cost calculator for road fuel rather than pipeline gas. Everything else is in the free online tools hub.
Frequently Asked Questions
It depends on the heating value. At the 2025 US average of about 1,037 BTU per cubic foot, one Ccf is 1.037 therms. Your own bill states the factor that applies to your meter, and it is the only one that will reconcile with your usage.
A therm is exactly 100,000 BTU. A dekatherm is ten therms, or one million BTU, and is the same quantity as one MMBtu. Residential bills usually use therms; wholesale contracts usually use dekatherms.
Because converting a volume of gas into an amount of energy is not a fixed ratio. It requires the heating value of the specific gas being delivered, which varies by region, by supplier and over time, so it has to be an input rather than a constant.
No. It means one thousand, from the Roman numeral, so an Mcf is one thousand cubic feet. A million cubic feet is written MMcf. This is the most common misreading in the whole vocabulary.
If the bill shows both therms and Ccf for the same period, divide the therms by the Ccf and multiply by 1,000. That gives BTU per cubic foot. Utilities also publish the figure in their rate schedules.
As raw energy, yes — 100,000 BTU divided by 3,412.14 BTU per kilowatt-hour gives 29.3. That is not the same as saying a therm of gas heats a house as much as 29.3 kilowatt-hours of electricity, because appliance efficiency differs.
Check whether the meter records in cubic feet or hundreds of cubic feet, and check whether the utility applies a pressure correction factor. Both are common and both change the number by a fixed multiplier.
No. It makes no external requests. You enter the price you are charged and the unit it is quoted in, which is the only way to get a figure that matches your own contract.
This tool performs unit arithmetic on figures you enter. It is not a billing statement, does not audit your utility account, and does not constitute energy or financial advice. Confirm any figure that affects a payment against your own bill and rate schedule.
