million BTU
Energyexact by definition
The MMBTU is one million International Table BTU, exactly 1.05505585262 × 10⁹ joules, or 1.055 GJ. It is the unit of the wholesale energy market: natural gas futures, LNG cargoes and industrial fuel contracts are all priced per MMBTU.
Watch out: MM means million here and mega everywhere else in the modern world, so MMBTU is a thousand times an "MBTU" in oil and gas usage and equal to it under SI reading. HVAC compounds the problem with MBH, which means a thousand BTU per hour. When a document mixes the two conventions, work from the magnitude of the number rather than the prefix.
| 1 MMBTU | 1,055,055,900 J |
The double M is Roman: M for a thousand, so MM is a thousand thousand. The convention comes from the oil and gas industry, where MCF has always meant a thousand cubic feet and MMCF a million.