BTU to JoulesFree online conversion calculator — instant results, no sign-up
Convert British thermal units to joules and back.
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About the BTU to Joules
The BTU to Joules calculator converts an energy amount in British thermal units (BTU) to joules and provides the reciprocal conversion for converting joules back to BTU. It uses 1 BTU = 1,055.055853 joules, so the default input of 1 BTU produces 1,055.055853 joules.
- Value in BTU (BTU)
- The energy amount to convert, expressed in British thermal units (BTU), with a default value of 1.
Formula and method
E_J = E_BTU × 1,055.055853; reverse conversion: E_BTU = E_J ÷ 1,055.055853.
- E_JEnergy expressed in joules (J).
- E_BTUEnergy expressed in British thermal units (BTU).
Multiply the entered BTU value by 1,055.055853 to obtain joules. With the default input, E_J = 1 × 1,055.055853 = 1,055.055853 joules. For the reverse conversion, divide the joule amount by the same factor; the reciprocal displayed for 1 joule is 0.000948 BTU, rounded to six decimal places.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Value in BTU1 BTU
Results
- joules1,055.055853
- 1 BTU =1,055.055853 joules
- 1 joules =0.000948 BTU
How to use the BTU to Joules
- 1Enter the energy amount in the Value in BTU (BTU) field, or leave the default value of 1.
- 2Read the calculated joules output, obtained by multiplying the BTU input by 1,055.055853.
- 3For the default input, confirm that the joules result is 1,055.055853.
- 4Read the unit-equivalence rows to check the forward factor and the rounded reverse factor.
- 5To convert joules back to BTU, divide the joule amount by 1,055.055853 rather than relying on the rounded reverse factor.
Reading your result
The 'joules' row is the converted energy for your entered BTU amount; with the default input it reads 1,055.055853. The '1 BTU' row states the fixed forward equivalence: 1 BTU = 1,055.055853 joules. The '1 joules' row states the rounded reciprocal equivalence: 1 joule = 0.000948 BTU. These equivalence rows describe unit relationships, not additional energy amounts to add to the result.
Limitations
The factor used here corresponds to the International Table BTU convention, rounded to the precision shown; other BTU definitions, such as the thermochemical BTU, have slightly different conversion factors. The displayed reverse factor of 0.000948 is rounded and can introduce avoidable error if used for further calculations. Conversion does not improve the accuracy of the original measurement. This tool converts energy, not power: BTU per hour is not interchangeable with BTU.
Common questions
What result does the default input of 1 BTU produce?+
It produces 1,055.055853 joules using the calculator's stated BTU-to-joule factor.
How do I convert joules back to BTU accurately?+
Divide the joule amount by 1,055.055853. The displayed equivalence of 1 joule = 0.000948 BTU is rounded, so division by the forward factor retains more precision.
Why might another BTU converter show a slightly different result?+
BTU has multiple definitions. This calculator uses a factor corresponding to the International Table BTU convention, while a converter using the thermochemical BTU or different rounding may give a slightly different result.
Can I enter an air conditioner's BTU-per-hour rating?+
Not directly as an energy amount. BTU per hour measures power; multiply that rating by an operating duration in hours to obtain BTU, assuming the stated rate remains constant, then convert that energy to joules.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
Further reading
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Results are estimates for informational purposes and are not financial, medical or legal advice.