Utilities
Energy Converter
Convert an energy value between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, BTU, and foot-pounds locally in your browser.
Convert energy between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, British thermal units, and foot-pounds. Zero is a valid value.
Conversions run locally in your browser; your energy value is not uploaded or stored.
Convert one energy value into the units you need.
Enter a non-negative energy value and choose its unit to see the equivalent joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, British thermal units, and foot-pounds. Zero is valid. It runs locally in your browser, so your value is not uploaded or stored.
Frequently Asked Questions
Everything you need to know about this tool, how it works, and privacy.
Which energy units can I convert?
Enter an energy value in joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, British thermal units, or foot-pounds. The converter returns the equivalent value in all eight units using 1 cal = 4.184 J, 1 kcal = 4,184 J, 1 Wh = 3,600 J, 1 kWh = 3,600,000 J, 1 BTU = 1,055.05585262 J, and 1 ft·lbf = 1.3558179483314004 J.
Can I convert zero or decimal energy values?
Yes. Zero is a valid energy value, and decimal values are accepted. Negative values are rejected because an energy amount cannot be less than zero. Results show up to six decimal places when needed.
What happens with very large energy values?
The converter shows an error when the entered value is too large to convert safely, instead of returning an unreliable rounded result.
Does my energy value leave my browser?
No. The conversion and copy action run locally in your browser. CodeASystem does not upload or store the value you enter.