How this calculator works
Natural gas is measured both by volume at the meter and by energy content when it is sold as fuel. One cubic foot of gas releases roughly 1,000 to 1,050 Btu, so the same physical gas can be quoted as a volume, as an energy, or as a larger billing multiple. Mcf means one thousand cubic feet and MMcf means one million cubic feet, using the Roman M for thousand and MM for thousand thousands. A therm is 100,000 Btu, a barrel of oil equivalent is about 5.8 million Btu, and a megajoule is one million joules.
Formula
cubic metres = entered value x F(volume unit). joules = cubic metres / 0.028316846592 x heat content (Btu/ft³) x 1,055.05585262. For an energy input, joules = entered value x F(energy unit), then cubic metres = joules / 1,055.05585262 / heat content x 0.028316846592. One Mcf = 1,000 ft³, one MMcf = 1,000,000 ft³, one therm = 100,000 Btu and one BOE = 5,800,000 Btu.
Worked example
1 Mcf at 1,037 Btu/ft³ is 1,037,000 Btu or 10.37 therms. 1,000 m³ is about 35,315 ft³ or 35.315 Mcf. 1 therm is 0.1 MMBtu. 1 BOE is 5.8 MMBtu.
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Frequently asked questions
What do Mcf and MMcf mean?
Mcf is one thousand cubic feet and MMcf is one million cubic feet. The M is the Roman numeral for one thousand, so MM is one thousand thousands. The metric mcm and mmcm use m3 rather than ft3 and are different, larger quantities.
Why is the heat content an input?
Natural gas is mostly methane but its composition varies, so one cubic foot can hold between roughly 1,000 and 1,050 Btu. Using a fixed average would give a slightly wrong energy answer for a specific supply.
Is a BOE exactly one barrel of oil?
No. It is an energy-equivalence convention of about 5.8 million Btu, close to the energy in one barrel of crude oil. A barrel of a particular crude may differ.