Energy converters

Energy converters cover a uniquely wide range: a chemical bond is a few eV, a heartbeat is about 1 J, an espresso machine uses around 100 kJ of electricity per shot, and a US household consumes roughly 30 kWh per day. All factors here are exact: 1 cal = 4.184 J (thermochemical), 1 BTU (IT) = 1055.05585262 J, 1 kWh = 3,600,000 J, 1 eV = 1.602176634 × 10⁻¹⁹ J (2019 SI).

Popular energy conversions

Joules to Kilojoules

J → kJ

Joules to Calories

J → cal

Joules to Kilocalories

J → kcal

Joules to Watt-hours

J → Wh

Joules to Kilowatt-hours

J → kWh

Kilojoules to Calories

kJ → cal

Kilojoules to Kilocalories

kJ → kcal

Kilojoules to Watt-hours

kJ → Wh

Kilojoules to Kilowatt-hours

kJ → kWh

Calories to Kilocalories

cal → kcal

Calories to Watt-hours

cal → Wh

Calories to Kilowatt-hours

cal → kWh

Kilocalories to Watt-hours

kcal → Wh

Kilocalories to Kilowatt-hours

kcal → kWh

Watt-hours to Kilowatt-hours

Wh → kWh

US therms to Kilowatt-hours

thm → kWh

US therms to BTU

thm → BTU

Foot-pounds (energy) to Joules

ft·lbf → J

All energy units

The 10 units below can be selected as source or target inside any energy converter.

Joules
J · Metric
Kilojoules
kJ · Metric
Calories
cal · Metric
Kilocalories
kcal · Metric
Watt-hours
Wh · Metric
Kilowatt-hours
kWh · Metric
BTU
BTU · Imperial
US therms
thm · US customary
Foot-pounds (energy)
ft·lbf · Imperial
Electronvolts
eV · Metric

Energy units in terms of the joule

Every energy unit on Convertitive is defined as an exact ratio of the joule (J), the reference unit for this category. The table below shows what one of each unit equals in joules — the constant every converter on this page is built from.

Energy units expressed in joules
Unit	Symbol	1 unit in joules
Joules	J	base unit
Kilojoules	kJ	1000 J
Calories	cal	4.184 J
Kilocalories	kcal	4184 J
Watt-hours	Wh	3600 J
Kilowatt-hours	kWh	3600000 J
BTU	BTU	1055.06 J
US therms	thm	105480400 J
Foot-pounds (energy)	ft·lbf	1.35582 J
Electronvolts	eV	1.6022 × 10^−19 J

To convert between any two units, Convertitive scales the input to joules using these factors and then back out to the target unit — so every result on this page traces to a single, exact definition rather than a chained approximation. Pick any pair above to see the formula, a 50-row reference table, and worked examples.

Joules to kilojoules reference table

Common joules values with their kilojoules equivalent, computed with the same factors the converter uses.

J	kJ
0.001	1.0000 × 10^−6
1	0.001
20	0.02
250	0.25
3600	3.6
25000	25
1000000	1000
10000000	10000
500000000	500000
10000000000	10000000
10000000000000	10000000000
1.0000 × 10^17	100000000000000

Need a value that is not listed? Open the J to kJ converter and type any number.