Gj to MMBTU Conversion Calculator

Enter gigajoules or MMBtu into the calculator to convert to the other value.

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 are rounded to 6 decimals in the calculator; displayed tables are rounded to 3 decimals.

When to Use This Calculator

Converting gas bills or energy specs in GJ to market quotes in $/MMBtu (and back).
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.

\mathrm{MMBtu}_{\mathrm{IT}} = \frac{\mathrm{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)
0.10	0.095
0.25	0.237
0.50	0.474
0.75	0.711
1	0.948
1.5	1.422
2	1.896
2.5	2.370
3	2.843
4	3.791
5	4.739
7.5	7.109
10	9.478
15	14.217
20	18.956
25	23.695
30	28.435
40	37.914
50	47.393
100	94.782
* 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)