Convert joules to btu instantly. Enter a value below, or use the formula and reference table further down the page.
In practice
Joules to BTU divides by 1,055.06, since one British thermal unit equals about 1,055 joules. BTUs are used for heating and cooling capacity in the US: air conditioners are rated 5,000 to 24,000 BTU per hour, and a gas boiler or heater may be 20,000 BTU/h or more. A joule is tiny, so values are normally in kilojoules or megajoules; one kilowatt-hour is 3.6 megajoules, or about 3,412 BTU. Use the conversion when comparing appliance ratings from the US with metric specifications.
How to convert joules to btu
Multiply the value by 0.0009478171.
BTU = J × 0.0009478171Example: 10 J = 0.0095 BTU.
Joules to BTU conversion table
| Joules (J) | BTU (BTU) |
|---|---|
| 1 J | 0.0009 BTU |
| 2 J | 0.0019 BTU |
| 3 J | 0.0028 BTU |
| 4 J | 0.0038 BTU |
| 5 J | 0.0047 BTU |
| 10 J | 0.0095 BTU |
| 15 J | 0.0142 BTU |
| 20 J | 0.019 BTU |
| 25 J | 0.0237 BTU |
| 50 J | 0.0474 BTU |
| 100 J | 0.0948 BTU |
Frequently asked questions
How many btu is 1 joule?
1 joule equals 0.0009 btu.
What is the formula to convert J to BTU?
To convert J to BTU, multiply the value by 0.0009478171. The full formula is: BTU = J × 0.0009478171.
How do I convert btu back to joules?
Use the same calculator above and type your value into the btu field instead — it converts in both directions. Or use the reverse formula: J = BTU ÷ 0.0009478171.
Is the J to BTU conversion exact?
The conversion factor used here (0.0009478171) is the standard internationally defined value. Results on this page are rounded to four decimal places for readability.