Fuel Efficiency Volume Converter

This converter is for the energy content of a fuel per unit of volume, also called its volumetric energy density or heating value: how many joules, kilocalories, Btu or therms each cubic meter, liter or cubic foot of it holds. Its SI unit is the joule per cubic meter (J/m³), but fuels are usually quoted in MJ/m³ for gases and MJ/L for liquids.

Natural gas holds about 38 MJ/m³, or about 1,000 Btu/ft³. Petrol (gasoline) holds about 34 MJ/L, and diesel about 36 MJ/L.

The last three units turn it around, as the volume of fuel needed for a given amount of energy.

How to convert energy per volume

Type a value into any field, and every other unit is calculated at once. For example, natural gas at 1,000 Btu/ft³:

1. In MJ/m³: multiply by 0.0372589.

   1,000 × 0.0372589 = 37.26 MJ/m³

2. In kJ/m³: multiply that by 1,000.

   37.26 × 1,000 = 37,260 kJ/m³

A liquid fuel in MJ/L is entered in the J/L field as joules: diesel's 36 MJ/L is 36,000,000 J/L, which shows as 36,000 MJ/m³.

Common conversions

The Btu and calorie values are the International Table (IT) units.

Energy per volume units

• Joule / meter³ (J/m³): The amount of energy, in joules, produced or consumed per cubic meter of volume.
  Conversion Factor: 1 J/m³ = 1 J/m³ (Base Unit)

• Joule / liter (J/l): Energy content measured in joules per liter of volume.
  Conversion Factor: 1 J/L = 1,000 J/m³

• Megajoule / meter³ (MJ/m³): Energy content in megajoules per cubic meter.
  Conversion Factor: 1 MJ/m³ = 1,000,000 J/m³

• Kilojoule / meter³ (kJ/m³): Energy content in kilojoules per cubic meter.
  Conversion Factor: 1 kJ/m³ = 1,000 J/m³

• Kilocalorie (IT) / meter³ (kcal/m³): Energy content measured in kilocalories (International Table) per cubic meter.
  Conversion Factor: 1 kcal/m³ = 4,186.8 J/m³

• Calorie (IT) / centimeter³ (cal/cm³): Energy content measured in calories (International Table) per cubic centimeter.
  Conversion Factor: 1 cal/cm³ = 4,186,800 J/m³

• Therm / foot³ (therm/ft³): Energy content in therms per cubic foot.
  Conversion Factor: 1 therm/ft³ ≈ 3,725,894,617 J/m³

• Therm / gallon (UK) (therm/gal): Energy content in therms per UK gallon.
  Conversion Factor: 1 therm/gal ≈ 23,207,984,510 J/m³

• Btu / foot³ (Btu/ft³): Energy content in British Thermal Units per cubic foot.
  Conversion Factor: 1 Btu (IT) / ft³ ≈ 37,259 J/m³; 1 Btu (th) / ft³ ≈ 37,234 J/m³

• CHU / foot³ (CHU/ft³): Energy content in Centigrade Heat Units per cubic foot.
  Conversion Factor: 1 CHU/ft³ ≈ 67,066 J/m³

The following are reciprocal units, revealing the volume of a substance required to produce a certain amount of energy:

• Meter³ / joule (m³/J): The volume of a substance required to produce or consume one joule of energy in cubic meters.
  Conversion Factor: 1 m³/J = 1 / (J/m³)

• Liter / joule (l/J): The volume of a substance required to produce or consume one joule of energy in liters.
  Conversion Factor: 1 l/J = 1,000 / (J/m³)

• Gallon (US) / horsepower (gal/hp): The volume in US gallons required to produce or consume one horsepower-hour of energy, about 2.68 million joules.
  Conversion Factor: 1 gal/hp ≈ 709,175,035 / (J/m³)