Convert

Kilojoule to Joule

Exact answer: 1 kJ = 1000 J (exact – SI decimal prefix)

Kilojoule and Joule both belong to the Energy family. The difference is a decimal prefix, so the factor is a clean power of ten. Energy appears in electricity tariffs, food labels, heating costs and technical datasheets.

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What do you want to convert?

From1 kJ

Result1,000 J

Factor1 kJ = 1000 J

Source basisBIPM SI Brochure · NIST Guide to SI Appendix B

Examples

011 kJ = 1,000 J

Example value from the reference table. Internal calculation uses stored factors; display output is rounded.

02Common mistake

Food calories are kilocalories. Utility bills use kilowatt-hours. Both are energy units, but in different contexts.

03Base unit: J

1 kJ = 1000 J. Then the value is converted through the base unit J into Joule.

Table

Kilojoule to Joule
Kilojoule	Joule
1	1,000
5	5,000
10	10,000
50	50,000
100	100,000
1,000	1,000,000

Formula

1 kJ = 1000 J. Then the value is converted through the base unit J into Joule.

Sources

BIPM SI BrochureSI base units, prefixes and official SI context.NIST Guide to SI Appendix BNIST conversion-factor method and non-SI factors.

Related conversions

Kilowatt-hour to JoulekWh → JEnergy Joule to Kilowatt-hourJ → kWhEnergy Kilocalorie to Kilojoulekcal → kJEnergy Kilojoule to KilocaloriekJ → kcalEnergy

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Factor origin

Factors come from the stored source family and are not derived from rounded display values.

Rounding rule

UnitCloud keeps calculating with stored factors and rounds only the displayed output by selected precision.

When not to use

Do not use as the sole basis for official, medical, safety-critical or contractual decisions.

Citation

Citation note: UnitCloud, conversion with formula, sources reviewed: September 2026. Energy. Source basis: BIPM SI Brochure · NIST Guide to SI Appendix B.

Common questions

What is the factor for Kilojoule to Joule?

1 kJ = 1000 J

Which formula does Kilojoule to Joule use?

1 kJ = 1000 J. Then the value is converted through the base unit J into Joule.

What is the most common mistake?

Food calories are kilocalories. Utility bills use kilowatt-hours. Both are energy units, but in different contexts.

When should I verify the result?

Do not use as the sole basis for official, medical, safety-critical or contractual decisions.