How it’s calculated
Everything is converted through the joule (J), the SI unit of energy. One watt-hour is one watt for one hour, i.e. 3,600 J.
Example: 1 kWh = 3,600,000 J ÷ 1,055.05585262 J/BTU ≈ 3,412.14 BTU.
The food "Calorie" on nutrition labels is a kilocalorie. Calorie definitions vary slightly (thermochemical 4.184 J, International Table 4.1868 J); this converter uses the thermochemical calorie.
Frequently asked questions
How many BTU are in a kWh?
About 3,412.14 BTU. One kWh is 3.6 million joules and one BTU is 1,055.056 joules.
Is a food Calorie the same as a calorie?
No. A food Calorie (capital C) is a kilocalorie: 1,000 small calories, or about 4.184 kJ.
How do I convert kcal to kJ?
Multiply by 4.184. For example, 2,000 kcal × 4.184 = 8,368 kJ.
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Sources
- NIST Guide to the SI, Appendix B: Conversion Factors (SP 811) — U.S. National Institute of Standards and Technology
- The International System of Units (SI Brochure) — BIPM
Formulas are taken from the free public references above. Results are provided “as is” for informational and educational purposes only. See our disclaimer.
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