Unit converter

Energy converter

Convert joules, calories, watt-hours, BTU, foot-pounds, and electronvolts.

Enter a value and choose units. Results update instantly.

1 kJ = 0.2390057361 kcal

All Energy units

From 1 kJ
UnitValue
Joule J 1,000
Kilojoule kJ 1
Thermochemical calorie cal 239.0057361377
Kilocalorie kcal 0.2390057361
Watt-hour Wh 0.2777777778
Kilowatt-hour kWh 0.0002777778
BTU (International Table) BTUₕᵀ 0.9478171203
Foot-pound ft·lb 737.5621492773
Electronvolt eV 6.2415090745e21
Recent conversions
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Common tasks

Kilojoule to KilocaloriekJ to kcal Kilocalorie to Kilojoulekcal to kJ Kilowatt-hour to JoulekWh to J BTU (International Table) to KilojouleBTUₕᵀ to kJ Watt-hour to JouleWh to J Foot-pound to Jouleft·lb to J

Reference

How energy conversion works

Energy appears in electricity, heat, food, and mechanics. Calorie and BTU definitions vary, so this converter labels and uses the thermochemical calorie and International Table BTU.

Values are converted to joule first, then from that reference into the requested unit. Keeping a single documented reference reduces inconsistent pair-by-pair constants.

Accuracy note: The thermochemical calorie and International Table BTU are named explicitly to avoid ambiguous legacy definitions.

Unit reference

UnitSymbol1 unit in J
JouleJ1
KilojoulekJ1,000
Thermochemical caloriecal4.184
Kilocaloriekcal4,184
Watt-hourWh3,600
Kilowatt-hourkWh3,600,000
BTU (International Table)BTUₕᵀ1,055.05585262
Foot-poundft·lb1.355817948331
ElectronvolteV1.602176634e-19

Long-tail directory

Every indexed conversion

Choose a source unit to see all available destinations.

From Joule (J)
Joule to KilojouleJoule to Thermochemical calorieJoule to KilocalorieJoule to Watt-hourJoule to Kilowatt-hourJoule to BTU (International Table)Joule to Foot-pound
From Kilojoule (kJ)
Kilojoule to JouleKilojoule to Thermochemical calorieKilojoule to KilocalorieKilojoule to Watt-hourKilojoule to Kilowatt-hourKilojoule to BTU (International Table)Kilojoule to Foot-pound
From Thermochemical calorie (cal)
Thermochemical calorie to JouleThermochemical calorie to KilojouleThermochemical calorie to KilocalorieThermochemical calorie to Watt-hourThermochemical calorie to Kilowatt-hourThermochemical calorie to BTU (International Table)Thermochemical calorie to Foot-pound
From Kilocalorie (kcal)
Kilocalorie to JouleKilocalorie to KilojouleKilocalorie to Thermochemical calorieKilocalorie to Watt-hourKilocalorie to Kilowatt-hourKilocalorie to BTU (International Table)Kilocalorie to Foot-pound
From Watt-hour (Wh)
Watt-hour to JouleWatt-hour to KilojouleWatt-hour to Thermochemical calorieWatt-hour to KilocalorieWatt-hour to Kilowatt-hourWatt-hour to BTU (International Table)Watt-hour to Foot-pound
From Kilowatt-hour (kWh)
Kilowatt-hour to JouleKilowatt-hour to KilojouleKilowatt-hour to Thermochemical calorieKilowatt-hour to KilocalorieKilowatt-hour to Watt-hourKilowatt-hour to BTU (International Table)Kilowatt-hour to Foot-pound
From BTU (International Table) (BTUₕᵀ)
BTU (International Table) to JouleBTU (International Table) to KilojouleBTU (International Table) to Thermochemical calorieBTU (International Table) to KilocalorieBTU (International Table) to Watt-hourBTU (International Table) to Kilowatt-hourBTU (International Table) to Foot-pound
From Foot-pound (ft·lb)
Foot-pound to JouleFoot-pound to KilojouleFoot-pound to Thermochemical calorieFoot-pound to KilocalorieFoot-pound to Watt-hourFoot-pound to Kilowatt-hourFoot-pound to BTU (International Table)

Primary source

Definitions and standards

Conversion constants and definitions for this category are checked against NIST SP 811: Energy units.

See Methods & sources for rounding rules, exact-value handling, and review policy.

Questions

Energy FAQ

What is the reference unit for energy conversions?

ConvertWin uses joule (J) as the internal reference for this category, then converts to the selected output unit.

How accurate is this energy converter?

The thermochemical calorie and International Table BTU are named explicitly to avoid ambiguous legacy definitions.