Energy unit converter
Stable Version 0.2.0Convert energy between kWh, MWh, Btu, therms, joules, and common fuels, with every constant and its source shown.
Converted amount
40.95MMBtu
12 MWh is 40.95 MMBtu.
NIST SP 811 · EIACross-checked · Five worked examples, built from the cited NIST and EIA constants, pass within their tolerances. Btu, watt-hour, kilowatt-hour, therm, and quad conversions agree with NIST SP 811 Appendix B.8 to every figure NIST prints. Fuel conversions reproduce EIA's published averages, which have no independent source. What this means
Example values · Review pending Report a problem
How we got this
Method
Convert the amount to joules with its unit's definition, then from joules to the target unit. Fuels use EIA's published average heat content in Btu.
Steps
- Convert MWh to joules: 1 MWh = 3.6 GJ.
- Convert joules to MMBtu: 1 MMBtu = 1,000,000 Btu.
- So 1 MWh = 3.41214 MMBtu. 12 × 3.41214 = 40.9457.
- Every constant here is exact by definition.
Constants
- 1 MWh = 3.41214 MMBtu (exact). Derived from the SI definitions (NIST SP 811)
- 1 MWh = 3.6 GJ (exact). NIST SP 811 (2008), Appendix B.8
- 1 MMBtu = 1,000,000 Btu (exact). EIA, British thermal units (Btu)
Assumptions
- Btu means the International Table Btu, 1,055.05585262 joules.
- A therm is 100,000 Btu (International Table), as EIA defines it. NIST SP 811 calls this the therm (EC); its therm (U.S.) is about 0.024% smaller.
- Fuel heat contents are US averages for the year shown, not the content of any one delivery.
Sources
- NIST Special Publication 811, Guide for the Use of the International System of Units, 2008, Appendix B.8, British thermal unit (IT) and kilowatt hour to joule
- EIA, Heat Content of Natural Gas Consumed, Annual, 2025, US, delivered to consumers, Btu per cubic foot
- EIA, Monthly Energy Review, Appendix A, Table A1, approximate heat content of petroleum products
- EIA, Energy conversion calculators, 2026 estimates, Coal, electric power sector, Btu per short ton
- EIA, British thermal units (Btu), Energy Explained, Therm and MMBtu definitions
Known limits
- Fuel results use national averages; the gas or oil you buy can differ by a few percent.
- The coal figure is EIA's estimate for coal burned in power plants, not for home or industrial coal.
- Volumes and weights of fuels are not converted to each other except through their energy.