Convert megajoules to kilojoules

1 MJ=1,000kJ

Use the converter below to change any megajoules value into kilojoules instantly — with formula, conversion table, and real-world examples.

You have

Equals

1,000

Conversion formula

Forward

kilojoules = megajoules × 1,000

Reverse

megajoules = kilojoules × 0.001

Example: 10 MJ × 1,000 = 10,000 kJ.

About both units

From

Megajoule

The megajoule equals 1,000,000 joules. Used for fuel energy content, large-scale mechanical work and in some European natural-gas billing. A litre of petrol contains about 34 MJ of energy.

Real-world: 1 L petrol: ~34 MJ. 1 L diesel: ~38 MJ. Tesla Model 3 full charge: ~270 MJ.

Read full megajoule reference →

Kilojoule

The kilojoule equals 1000 joules. Used on European nutrition labels (required by EU law alongside kcal), for mechanical work specifications, and some engineering contexts. A 100 g chocolate bar contains about 2100 kJ.

Real-world: 100 g chocolate: ~2100 kJ. EU daily intake (adult): ~8400 kJ. Tesla Model 3 battery: ~270 MJ = 270,000 kJ.

Read full kilojoule reference →

Megajoule to Kilojoule conversion table

Common megajoules to kilojoules values for quick reference.

Megajoule (MJ)	Kilojoule (kJ)
1 MJ	1,000 kJ
10 MJ	10,000 kJ
100 MJ	100,000 kJ
500 MJ	500,000 kJ
1,000 MJ	1,000,000 kJ
5,000 MJ	5,000,000 kJ
10,000 MJ	10,000,000 kJ
50,000 MJ	50,000,000 kJ
100,000 MJ	100,000,000 kJ
500,000 MJ	500,000,000 kJ

Tips & common mistakes

Quick tips

1 MJ = 1000 kJ = 0.278 kWh.
Natural gas heat content often quoted as MJ/m³.
For fuel economy, use MJ/km or L/100km interchangeably.

Avoid these

Confusing MJ with MW (power).
Using MJ for electricity bills — kWh is standard.
Mixing fuel energy (MJ) with fuel volume (L) without unit conversion.

Frequently asked questions

How many kilojoules in a megajoule?

One megajoule equals 1,000 kilojoules.

How do I convert megajoules to kilojoules?

Multiply the megajoule value by 1,000 to get the equivalent in kilojoules.

What is 100 megajoules in kilojoules?

100 megajoules equals 100,000 kilojoules.

Is a megajoule bigger than a kilojoule?

Yes. 1 megajoule equals 1,000 kilojoules, so one megajoule is larger.

How to convert megajoules to kilojoules without a calculator?

Multiply by 1,000 for a quick estimate; use a calculator for precise results.

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