British thermal unit.
BTU to Megajoules Converter — BTU to MJ
Convert BTU (BTU) to Megajoule (MJ) using the exact conversion factor (1 btu = 0.0010550559 megajoule). See the formula, worked examples, conversion table, history, and common uses.
BTU to Megajoules converter
Converter
Energy Converter
Convert joules, calories, kilowatt-hours, BTU, electronvolts, therms, and mechanical work units.
Context values
Some unit families need one extra value for a physically accurate result.
Megajoule is 1000000 joule units.
Result = input x 1055.055853 / 1e+6.
Energy uses the joule as the base unit.
Reserved above the conversion cards and below the converter.
About Converting BTU to Megajoules
BTU and Megajoule both measure energy, and the conversion is especially useful for comparing nutrition labels (kilocalories) against scientific energy figures (joules). BTU is most often used for air conditioner and furnace capacity ratings in the us.
Formula
megajoules = btu × 0.00105505585262
This factor comes from each unit's defined relationship to the category's base unit: 1 btu equals 1055.05585262 base units, and 1 megajoule equals 1000000 base units, so dividing one by the other gives the direct btu-to-megajoule factor of 0.00105505585262.
Simple example
1 BTU × 0.001055055853 = 0.0010550559 MJ
1 btu = 0.0010550559 megajoules.
Real-world example
100 BTU × 0.001055055853 = 0.1055055853 MJ
100 btu = 0.1055055853 megajoules.
Conversion table
| BTU (BTU) | Megajoule (MJ) |
|---|---|
| 1 BTU | 0.0010550559 MJ |
| 10 BTU | 0.0105505585 MJ |
| 100 BTU | 0.1055055853 MJ |
| 500 BTU | 0.5275279263 MJ |
| 1,000 BTU | 1.055055853 MJ |
| 2,000 BTU | 2.110111705 MJ |
Reverse conversion: Megajoule to BTU
0.0010550559 MJ × 947.8171203 = 1.000000045 BTU
0.0010550559 megajoules = 1.000000045 btu.
btu = megajoules × 947.817120313
For a page dedicated to this direction, see Megajoule to BTU.
Understanding the BTU
BTU (BTU) measures energy. A British thermal unit is defined as exactly 1,055.05585262 joules (the International Table BTU). It is classified as a US customary unit.
Where it's used: United States (HVAC, heating, and appliance energy ratings)
Uses of the BTU today
- Air conditioner and furnace capacity ratings in the US
- Water heater and appliance energy specifications
- US energy industry (natural gas is often billed via BTU content)
History of the BTU
The BTU originated in 19th-century steam engineering as the heat needed to raise one pound of water by one degree Fahrenheit, paralleling the calorie's metric definition. Several slightly different BTU values existed historically before the 'International Table' BTU was standardized at exactly 1,055.05585262 joules.
Historical origin. BTU was not the invention of a single named person; it developed through the process described above.
Understanding the Megajoule (MJ)
Megajoule is 1000000 joule units.
BTU — sources
- NIST Special Publication 811 — Documents the International Table BTU's exact joule equivalence.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many megajoules are in 1 btu?
1 btu equals 0.0010550559 megajoules, using the exact defined conversion factor rather than an estimate.
How do I convert btu to megajoule?
Multiply the btu value by 0.001055055853. The converter above does this instantly to whatever precision you set.
How do I convert megajoule back to btu?
Use the reverse factor: 1 megajoule equals 947.8171203 btu. You can also use the swap control in the converter above to flip the direction instantly.
What is a btu?
BTU (BTU) measures energy. A British thermal unit is defined as exactly 1,055.05585262 joules (the International Table BTU). It is classified as a US customary unit.
What is a megajoule?
Megajoule (MJ) is a unit of energy.
Is the btu to megajoule conversion exact?
Yes. A British thermal unit is defined as exactly 1,055.05585262 joules (the International Table BTU). That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Where is the btu still used today?
United States (HVAC, heating, and appliance energy ratings)