Fuel Efficiency - Volume Converter
Convert between volume-basis fuel efficiency units — energy density (J/m³, Btu/ft³, MJ/m³) and volume-basis specific fuel consumption (gal/(hp·h)).
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
Result
1000 Btu/ft³ = 37.258946 MJ/m³
1 Btu (IT) per Cubic Foot = 0.037258946 Megajoules per Cubic Meter
1 Megajoule per Cubic Meter = 26.839192 Btu (IT) per Cubic Foot
1000 Btu/ft³ in every supported unit
What is a Fuel Efficiency - Volume Converter?
This converter handles two related but distinct volume-basis quantities on one page. The first group — joules per cubic meter, Btu per cubic foot, megajoules per cubic meter — is energy density, the calorific value packed into a fixed volume of fuel: it's exactly what natural gas utilities mean by "heating value" on a bill. The second group — cubic meters per joule, gallons per horsepower-hour — is volume-basis specific fuel consumption, how much fuel volume an engine actually burns to deliver one unit of output.
The two groups are mathematical reciprocals of each other, so this converter inverts automatically when you cross between them — the same reciprocal handling the site's Fuel Efficiency - Mass and Fuel Consumption converters use. Within a single group, conversions are plain multiplication.
Conversion chart: Btu (IT) per Cubic Foot to Megajoules per Cubic Meter
Conversion table
| Btu (IT) per Cubic Foot (Btu/ft³) | Megajoule per Cubic Meter (MJ/m³) |
|---|---|
| 0.01 Btu/ft³ | 0.00037258946 MJ/m³ |
| 0.1 Btu/ft³ | 0.0037258946 MJ/m³ |
| 1 Btu/ft³ | 0.037258946 MJ/m³ |
| 2 Btu/ft³ | 0.074517892 MJ/m³ |
| 3 Btu/ft³ | 0.11177684 MJ/m³ |
| 5 Btu/ft³ | 0.18629473 MJ/m³ |
| 10 Btu/ft³ | 0.37258946 MJ/m³ |
| 20 Btu/ft³ | 0.74517892 MJ/m³ |
| 50 Btu/ft³ | 1.8629473 MJ/m³ |
| 100 Btu/ft³ | 3.7258946 MJ/m³ |
| 1000 Btu/ft³ | 37.258946 MJ/m³ |
Supported Units
| Unit | Symbol | Category |
|---|---|---|
| Joule per Cubic Meter | J/m³ | Energy density (energy/volume) |
| Kilojoule per Cubic Meter | kJ/m³ | Energy density (energy/volume) |
| Megajoule per Cubic Meter | MJ/m³ | Energy density (energy/volume) |
| Joule per Liter | J/L | Energy density (energy/volume) |
| Btu (IT) per Cubic Foot | Btu/ft³ | Energy density (energy/volume) |
| Kilocalorie (IT) per Cubic Meter | kcal/m³ | Energy density (energy/volume) |
| Cubic Meter per Joule | m³/J | Specific fuel consumption (volume/energy) |
| Liter per Joule | L/J | Specific fuel consumption (volume/energy) |
| Gallon (US) per Horsepower-hour | gal/(hp·h) | Specific fuel consumption (volume/energy) |
About These Parameters
- Value
- The fuel-efficiency figure you want to convert, expressed in the "From" unit. Accepts decimals.
- From Unit
- The unit your input value is currently measured in — an energy-density unit like Btu/ft³ (natural gas heating value) or a volume-basis SFC unit like gal/(hp·h).
- To Unit
- The unit you want the result converted into. Use the swap button to flip From and To instantly.
How Fuel Efficiency - Volume Conversion Works
The Formula
Within the same group (both energy density, or both volume-basis SFC), conversion is a simple multiplication:
result = value × (factor of "From" unit ÷ factor of "To" unit)
Crossing between the two groups instead inverts through the base unit:
SFC unit = (factor of SFC unit) ÷ (value × factor of energy-density unit)
For Btu (IT) per Cubic Foot → Megajoule per Cubic Meter: 1000 Btu/ft³ = 37.258946 MJ/m³.
Natural Gas Heating Value
Btu per cubic foot is the figure US natural gas utilities print on customer bills and pipeline specifications — "pipeline-quality" gas is typically standardized around 1,000-1,050 Btu/ft³. A higher figure means more energy is delivered for the same metered volume of gas, which is why utilities monitor and adjust the heating value of blended gas supplies to stay within a contracted range.
Mass Basis vs. Volume Basis
This converter's companion, the Fuel Efficiency - Mass Converter, measures the same underlying idea (energy content and fuel consumption) but per unit of fuel mass instead of volume. The two only agree once you know the fuel's density — a liter of gasoline and a liter of diesel contain different masses, and therefore convert differently between the mass and volume versions of these units.
Example
Pipeline-quality natural gas rated at 1,000 Btu/ft³ converts to about 37.258946 MJ/m³ — the figure a European gas specification would use for the same fuel quality.
Frequently Asked Questions
What does "1,000 Btu" natural gas mean on my utility bill?
Utilities often bill natural gas by volume (hundred cubic feet, or "CCF"), then apply a heating-value factor close to 1,000-1,050 Btu per cubic foot to convert that volume into billed energy (therms). The exact figure varies slightly by gas source and blend, which is why bills sometimes show a "Btu factor" alongside the metered volume.
Why is there a separate Mass and Volume fuel efficiency converter?
Mass and volume only convert into each other through a fuel's density, which this page doesn't assume. Use the Mass converter for calorific value and SFC figures reported per kilogram or pound; use this Volume converter for figures reported per liter, cubic meter, or gallon.
How accurate are these conversions?
Every conversion factor used here is the exact, internationally recognized relationship between the underlying energy and volume units (e.g. 1 Btu = exactly 1,055.05585262 joules) — results are limited only by floating-point display precision, not by rounded conversion constants.