Convert British Thermal Unit to Megajoule (BTU → MJ)

Converting BTU to megajoules is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1. 1
   Take your value in BTU

   Start with the number of BTU (BTU) you want to convert.
2. 2
   Multiply by 0.001055

   The conversion factor from BTU to MJ is 0.001055. Multiply your value by this number.
3. 3
   Read the result in megajoules

   The result is your value in megajoules (MJ).

Multiply the value in BTU by 0.001055. For the reverse direction, multiply by 947.81712.

• ✓1 BTU = 1055.06 J = 0.293 Wh.
• ✓BTU/h (power) and BTU (energy) are different — don't confuse.
• ✓Tons of refrigeration: 12,000 BTU/h = 1 ton AC.

• ✗Confusing BTU and BTU/h — energy vs power.
• ✗Using kcal when BTU is requested in HVAC specs.
• ✗Treating all BTUs as exact — definitions vary (IT, thermochemical, etc.).

What is the British Thermal Unit?

The British thermal unit (BTU) equals approximately 1,055.06 joules and is the standard unit in American HVAC, gas appliances, and air-conditioner ratings. Originally defined as the heat needed to raise 1 pound of water by 1°F, the BTU is the imperial counterpart to the calorie. American gas utilities measure delivered heat in BTUs or therms (1 therm = 100,000 BTU), and air conditioners are rated by their cooling capacity in BTU per hour (a typical window AC is 5,000–12,000 BTU/h, central AC for a medium home is 24,000–60,000 BTU/h). Furnaces are similarly rated. The BTU relates to the joule (1 BTU ≈ 1,055 J), the calorie (1 BTU ≈ 252 cal), the watt-hour (1 BTU ≈ 0.293 Wh), and the therm (100,000 BTU = 1 therm). Outside the United States, the BTU is rare; metric countries use kilojoules or kilowatt-hours for the same applications.

• US air-conditioner sizing
• US heating-system capacity
• Natural gas billing in some US regions

What is the Megajoule?

The megajoule equals 1,000,000 joules (or 1,000 kilojoules) and is used for measuring fuel energy content, large-scale electrical work, and industrial heat applications. The energy content of food and fuel is often quoted in MJ: a kilogram of gasoline contains about 46 MJ, natural gas has 38 MJ per cubic meter, and a kilogram of coal yields 24 MJ. Vehicle fuel-economy and energy-efficiency calculations use MJ to compare disparate energy sources. Industrial process heating, boiler outputs, and large machinery energy ratings are commonly given in MJ per cycle or MJ per hour. The megajoule relates to the joule (10⁶ J = 1 MJ), the kilojoule (1,000 kJ = 1 MJ), the kilowatt-hour (1 kWh = 3.6 MJ), and the BTU (1 MJ ≈ 948 BTU). For electricity-grid energy accounting, the equivalent kilowatt-hour or megawatt-hour is more common than MJ.

• Fuel energy content reporting
• Natural gas billing in some countries
• Industrial energy consumption