Energy & Work Converter: Joules, Calories, kWh & BTU

This energy converter instantly switches between joules, kilojoules, calories, kilocalories, kilowatt-hours, and BTU, the units that show up in nutrition labels, physics problems, and utility bills alike. It's designed for students solving physics or chemistry homework, home cooks or dieters comparing calorie and kilojoule labels, and homeowners trying to understand kWh and BTU figures on an energy bill or appliance spec sheet. Enter a value in any field and every other energy unit updates instantly, using precise standard conversion factors so there's no need to search for a formula or reference table. The tool is completely free, requires no signup, and works the same on a phone or desktop browser. Since every calculation runs locally in your browser, your inputs are never uploaded or stored anywhere, making the tool quick and fully private. Scroll down to enter an energy value and see it converted across every unit at once.