VastCalc
Conversion
Energy Converter
Convert between joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, and BTU.

Energy Converter

Convert between common energy units including joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, and BTU. All conversions use internationally standardized conversion factors.

Energy conversion spans multiple fields: physics uses joules, nutrition uses kilocalories (often just called 'Calories'), electrical engineering uses watt-hours, and HVAC systems use BTU.

Key Conversion Factors:

  • 1 thermochemical calorie = 4.184 joules (exact, by definition)
  • 1 kilocalorie (food Calorie) = 4,184 joules
  • 1 watt-hour = 3,600 joules (exact)
  • 1 kilowatt-hour = 3,600,000 joules (exact)
  • 1 BTU (International Table) = 1,055.056 joules
  • 1 kWh = 3,412.14 BTU
  • 1 kWh = 860.421 kcal

Practical Context:

  • A food Calorie (kcal) can raise 1 kg of water by 1°C
  • A 100W light bulb uses 0.1 kWh per hour
  • Heating a typical US home for a day uses roughly 100,000 BTU

Frequently Asked Questions

Search Calculators

Search across all calculator categories