Joules to BTU Converter

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Quick answer: To convert joules to BTU, multiply by 0.0009478171. For example, 10 J is 0.009478171 Btu. One joule equals 0.0009478171 Btu.

Use the Joules to BTU Converter

Joules to BTU formula and what each symbol means

Btu = J × 0.0009478171

Symbols used in the formula
SymbolMeaning
JJoule
BtuBritish thermal unit

Joules to BTU examples

1 J

1 J × 0.0009478171 = 0.0009478171 Btu.

10 J

10 J × 0.0009478171 = 0.009478171 Btu.

100 J

100 J × 0.0009478171 = 0.09478171 Btu.

Joules compared with BTU

One Btu is 1,055 times as large as one J, so your number gets smaller when you convert joules to BTU and bigger when you convert back. If the answer is not smaller than what you typed, you multiplied instead of dividing.

About joules and BTU

Joule (J): The SI unit of energy, one newton metre. British thermal unit (Btu): International Table British thermal unit, 1,055.05585262 joules.

Where joules to BTU conversions are used

Gas and heating are often billed in therms, BTU or megajoules. Engineering and physics calculations usually work in joules.

How to calculate Joules to BTU step by step

  1. Enter the value in J (the starting unit).
  2. Multiply by 0.0009478171, because 1 J = 0.0009478171 Btu.
  3. The product is the value in Btu. To go back, divide by 0.0009478171 or multiply by 1,055.056.

Popular energy conversions

How to read your Joules to BTU result

Quick estimate: multiply by about 0.00095 to get BTU from joules; this is within 0.3% of the exact factor. Food labels use the kilocalorie (kcal, written Calorie in the US), electricity bills use the kilowatt hour, and heating uses the Btu.

JOULESBTU
10.0009478171
20.001895634
50.004739086
100.009478171
200.01895634
500.04739086
1000.09478171
1,0000.9478171

BTU to Joules: quick table

BTUJOULES
11,055.056
55,275.279
1010,550.56
2526,376.4
5052,752.79
100105,505.6
250263,764
500527,527.9

Common mistakes when calculating Joules to BTU

  • Confusing kW (power) with kWh (energy).
  • Dividing when you should multiply: from J to Btu multiply by 0.0009478171; from Btu to J divide by 0.0009478171.

Joules to BTU FAQ

How many Btu are in 1 J?

1 J equals 0.0009478171 Btu.

How many J are in 1 Btu?

1 Btu equals 1,055.056 J.

Is 1 J = 0.0009478171 Btu an exact conversion?

Yes. The joule and the british thermal unit are both defined exactly in SI terms, so the ratio has no measurement uncertainty; 0.0009478171 is just that ratio shown to 7 significant figures.

What is a british thermal unit (Btu)?

International Table British thermal unit, 1,055.05585262 joules.

How can I estimate joules to BTU in my head?

Quick estimate: multiply by about 0.00095 to get BTU from joules; this is within 0.3% of the exact factor.

What is 150 J in BTU?

150 J = 0.1421726 Btu (since 150 × 0.0009478171).

What is 0.5 J in BTU?

0.5 J = 0.0004739086 Btu (since 0.5 × 0.0009478171).

What is 25 J in BTU?

25 J = 0.02369543 Btu (since 25 × 0.0009478171).

How many decimals should I keep when converting J to Btu?

Match the precision of your original measurement. For example, 0.009478171 Btu rounds to 0.00948 Btu at 3 significant figures; keep more digits only for engineering or scientific work.

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Method, review and disclaimer

Edited by: Hemant Kumar and Anjita Rai, founders of ToolsVault (SEO and content professional, not a licensed adviser). Method: this tool runs in your browser using the formula shown on this page; the numbers you enter are not sent to our servers. Sources: NIST SP 811, Appendix B.8: conversion factors