The British thermal unit (BTU) is the energy needed to raise one pound of water by one degree Fahrenheit, widely used for heating and air-conditioning ratings.
Btu to Millijoules
Convert British thermal unit (BTU) to Millijoule (mJ) instantly with an exact formula, conversion table, and FAQ.
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Convert btu (BTU) to millijoules (mJ) instantly with formula, conversion table, and FAQ.
Context values
Some unit families need one extra value for a physically accurate result.
A millijoule (mJ) is a metric-prefixed unit of energy equal to 10-3 joules, a fraction of a single joule, using the SI milli prefix.
mJ = BTU × 1055055.853
Results update instantly for Btu to Millijoules conversions.
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Formula
mJ = BTU × 1055055.853
BTU = mJ × 9.478171203e-07
Conversion table
| 1 BTU | 1.055056e+06 mJ |
| 5 BTU | 5.275279e+06 mJ |
| 10 BTU | 1.055056e+07 mJ |
| 20 BTU | 2.110112e+07 mJ |
| 50 BTU | 5.275279e+07 mJ |
| 100 BTU | 1.055056e+08 mJ |
| 500 BTU | 5.275279e+08 mJ |
| 1000 BTU | 1.055056e+09 mJ |
Related conversions
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How the formula works
Both british thermal unit and millijoule measure the same physical quantity, so converting between them is a single multiplication. Multiply a value in btu by 1055055.853 to get millijoules. To reverse the conversion, multiply a millijoule value by 9.478171203e-07 to get back to btu.
Frequently asked questions
What is British thermal unit (BTU)?
The British thermal unit (BTU) is the energy needed to raise one pound of water by one degree Fahrenheit, widely used for heating and air-conditioning ratings.
What is Millijoule (mJ)?
A millijoule (mJ) is a metric-prefixed unit of energy equal to 10-3 joules, a fraction of a single joule, using the SI milli prefix.
How do I convert btu to millijoules?
Multiply the british thermal unit value by 1055055.853 to get the equivalent in millijoules. For example, 5 BTU × 1055055.853 = 5.275279e+06 mJ.
Is this conversion exact?
Yes. Both units are defined against the SI base unit for this dimension, so the factor 1055055.853 is an exact, non-rounded value.
Can I convert millijoules back to btu?
Yes. Divide the millijoule value by 1055055.853, or multiply it by 9.478171203e-07, to get btu.
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About converting btu to millijoules
The British thermal unit (BTU) is the energy needed to raise one pound of water by one degree Fahrenheit, widely used for heating and air-conditioning ratings. A millijoule (mJ) is a metric-prefixed unit of energy equal to 10-3 joules, a fraction of a single joule, using the SI milli prefix.
Use this calculator to move between btu and millijoules accurately for homework, engineering, billing, or everyday energy calculations. The Universal Converter uses exact unit factors, so results stay consistent across the site.