Energy: Joules ↔ calories ↔ kWh

Convert energy between Joules, food calories (kcal) and kilowatt-hours (kWh). All calculations are done locally in your browser.

Enter a value in one field (Joules, kcal or kWh), then click "Convert energy". The tool will automatically fill in the other units using standard physics conversions:

  • 1 kcal = 4,184 joules
  • 1 kWh = 3,600,000 joules

Base SI unit for energy.
Food calories (kilocalories).
Used on electricity bills.

This energy converter helps you quickly convert between Joules (J), kilocalories (kcal) and kilowatt-hours (kWh), three of the most commonly used energy units in physics, nutrition and electricity billing. Whether you need to convert food calories into joules, joules into kWh, or understand how energy consumption relates to electricity usage, this calculator provides instant and accurate results using standard scientific formulas.

All conversions are performed locally in your browser, with no data sent to any server. This makes the tool fast, private and reliable for students, engineers, athletes, nutrition tracking or anyone needing a simple energy unit converter.

Conversions use standard approximations: 1 kcal = 4 184 J and 1 kWh = 3 600 000 J. Results are rounded for readability.