Joules to BTU Converter
Convert joules to British thermal units — divide by 1,055.06. Results update as you type; exact factors shown.
One joule is 0.0009 British thermal units — see the exact factor, not a rounded rule of thumb.
How the joules to btu converter works
Energy converts through the joule. A thermochemical calorie is exactly 4.184 J, so a food Calorie (kcal) is 4.184 kJ. A kilowatt-hour is exactly 3.6 MJ. A BTU is 1,055.056 J and a US therm is 100,000 BTU.
The US uses customary units (US gallon, short ton, °F) in daily life; NIST SP 811 gives the exact SI factors.
Common energy conversions
| From | To | Units |
|---|---|---|
| 1,000 J | 0.9478 BTU | joules to British thermal units |
| 5,000 J | 4.7391 BTU | joules to British thermal units |
| 10,000 J | 9.4782 BTU | joules to British thermal units |
| 100,000 J | 94.7817 BTU | joules to British thermal units |
| 500,000 J | 473.9086 BTU | joules to British thermal units |
| 1,000,000 J | 947.8171 BTU | joules to British thermal units |
| 3,600,000 J | 3,412.1416 BTU | joules to British thermal units |
| 5,000,000 J | 4,739.0856 BTU | joules to British thermal units |
| 10,000,000 J | 9,478.1712 BTU | joules to British thermal units |
| 100,000,000 J | 94,781.712 BTU | joules to British thermal units |
| 1,000,000,000 J | 947,817.1203 BTU | joules to British thermal units |
| 10,000,000,000 J | 9,478,171.2031 BTU | joules to British thermal units |
Units in this converter and their exact factors
| Unit | Symbol | One unit in joules |
|---|---|---|
| joule | J | 1 joule |
| kilojoule | kJ | 1,000 joule |
| megajoule | MJ | 1,000,000 joule |
| calorie (thermochemical) | cal | 4.184 joule |
| kilocalorie (food Calorie) | kcal | 4,184 joule |
| watt-hour | Wh | 3,600 joule |
| kilowatt-hour | kWh | 3,600,000 joule |
| British thermal unit | BTU | 1,055.05585262 joule |
| therm (US) | thm | 105,505,585.262 joule |
| foot-pound | ft·lb | 1.3558179483 joule |
FAQFrequently asked questions about energy conversion
How many BTU in a joule?
0.000948 BTU — a joule is a small unit next to a BTU.
What is 3.6 MJ in BTU?
3,412 BTU, which is one kilowatt-hour.
Why convert?
Because heating equipment is rated in BTU in the US and in watts or joules elsewhere, and comparing them needs one unit.
What is 1 MJ in BTU?
948 BTU.
Is the BTU precisely defined?
Several definitions exist differing by fractions of a percent. This uses the international table value of 1,055.05585 J.
Where these figures come from
- BIPM — The International System of Units (SI Brochure, 9th edition) — definitions of the base and derived units.
- NIST Special Publication 811 — Guide for the Use of the International System of Units — the exact conversion factors used here.
- National Institute of Standards and Technology (NIST) — United States's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.