Convert gigajoules, megajoules, or kilowatt-hours to MMBtu or Btu, or convert MMBtu/Btu back to energy units from a single entered value.

MMBtu means one million Btu. Choose the IT or thermochemical definition used by your source.

Assumptions Assumptions
  • Conversions are energy-to-energy only—no HHV/LHV adjustments, fuel composition, or thermodynamic state corrections.
  • “MMBtu” is treated as one million Btu; both International Table (IT) and thermochemical (th) definitions are supported.
  • Unit standards: 1 GJ = 1e9 J; 1 MJ = 1e6 J; 1 kWh = 3.6e6 J; 1 MMBtu (IT) = 1.05505585262e9 J; 1 MMBtu (th) = 1.054350264488e9 J; 1 Btu (IT) = 1055.05585262 J.
  • Results use up to 6 decimal places, with scientific notation for very small or large values; displayed tables are rounded to 3 decimals.
When to Use This Calculator
  • Converting the energy amounts on gas bills or energy specifications between GJ and MMBtu. This tool does not convert prices per unit.
  • Normalizing plant or site energy data reported in GJ, MJ, or kWh to MMBtu for benchmarking.
  • Aligning engineering, utility, and regulatory documents that mix SI and imperial energy units.
Input Definitions
  • Gigajoules — enter energy in GJ, or choose MJ (1e6 J) or kWh (3.6e6 J).
  • MMBtu — choose IT or thermochemical; Btu (IT) is provided for convenience output.
  • Formulas — IT: MMBtu = GJ ÷ 1.05505585262; GJ = MMBtu × 1.05505585262. General: value(J) = value × unit_to_J; target = J ÷ target_to_J.

GJ to MMBtu Formula

The following formula converts gigajoules to MMBtu using the International Table (IT) definition; a thermochemical variant is also common.

MMBtuIT = (GJ) / (1.05505585262)
  • 1 GJ = 1,000,000,000 J
  • 1 kWh = 3,600,000 J
  • 1 MMBtu (IT) = 1,055,055,852.62 J
  • 1 MMBtu (th) = 1,054,350,264.488 J
  • 1 Btu (IT) = 1,055.05585262 J

GJ to MMBtu Conversion Table

Gigajoules to MMBtu (IT)
GJ MMBtu (IT)
0.100.095
0.250.237
0.500.474
0.750.711
10.948
1.51.422
21.896
2.52.370
32.843
43.791
54.739
7.57.109
109.478
1514.217
2018.956
2523.695
3028.435
4037.913
5047.391
10094.782
* IT definition: 1 MMBtu = 1.05505585262 GJ (1 GJ ≈ 0.94781712 MMBtu). Thermochemical: 1 MMBtu = 1.054350264488 GJ.

How do you convert GJ to MMBtu? Using the IT definition, multiply GJ by 0.94781712 (or divide by 1.05505585262). For the thermochemical definition, divide by 1.054350264488.

How do you convert MMBtu to GJ? Multiply MMBtu (IT) by 1.05505585262 to get GJ; for thermochemical MMBtu, multiply by 1.054350264488.

Example Problem

Convert 2.5 GJ to MMBtu (IT).

Use the IT formula: MMBtu = GJ ÷ 1.05505585262.

MMBtu = 2.5 ÷ 1.05505585262 ≈ 2.3695 MMBtu (IT)