Megajoule to Millijoule Converter

Energy Converter

27 units available

Decimals:

From

To

1,000,000,000

1 MJ = 1,000,000,000 mJ

Formula:

mJ = MJ × 1.000000e+9

With your value: 1 MJ = 1,000,000,000 mJ

How big is that?

Everyday references on a logarithmic scale, all expressed in megajoule so you can sanity-check the result.

Heartbeat (1/1.0e+6 your value)0.00000100 MJ

AA battery charge (1/1.0e+2 your value)0.0100 MJ

Slice of bread (1/3.6 your value)0.280 MJ

Your value1.00 MJ

Daily food intake (8.4× your value)8.40 MJ

Litre of petrol (34× your value)34.2 MJ

Other Megajoule to Millijoule conversions

2 MJ to mJ 3 MJ to mJ 4 MJ to mJ 5 MJ to mJ 6 MJ to mJ 7 MJ to mJ 8 MJ to mJ

Megajoule to Millijoule Conversion Table

Megajoule (MJ)	Millijoule (mJ)
0.5	500,000,000
1	1,000,000,000
2	2,000,000,000
5	5,000,000,000
10	10,000,000,000
15	15,000,000,000
20	20,000,000,000
25	25,000,000,000
50	50,000,000,000
100	100,000,000,000
250	250,000,000,000
500	500,000,000,000
1000	1.000000e+12

Millijoule to Megajoule Conversion Table

Millijoule (mJ)	Megajoule (MJ)
0.5	5.000000e-10
1	1.000000e-9
2	2.000000e-9
5	5.000000e-9
10	1.000000e-8
15	1.500000e-8
20	2.000000e-8
25	2.500000e-8
50	5.000000e-8
100	1.000000e-7
250	2.500000e-7
500	5.000000e-7
1000	1.000000e-6

Where these values come from

Every factor on this page is traced to the document that defines it. See the full provenance dataset or our methodology.

Megajoule (MJ)

Energy

Exact conversion

Derived from the joule (1 J = 1 kg·m²/s²). Thermochemical and IT calories, BTU and kWh are exact defined multiples.

Source: NIST Special Publication 811, Guide for the Use of the International System of Units

National Institute of Standards and Technology (US) · Reviewed 2026-07-01

Millijoule (mJ)

Energy

Exact conversion

Derived from the joule (1 J = 1 kg·m²/s²). Thermochemical and IT calories, BTU and kWh are exact defined multiples.

Source: NIST Special Publication 811, Guide for the Use of the International System of Units

National Institute of Standards and Technology (US) · Reviewed 2026-07-01

How to Convert Megajoule to Millijoule

To convert from Megajoule (MJ) to Millijoule (mJ), multiply the value by 1,000,000,000.

Formula: mJ = MJ × 1.000000e+9

Reverse: MJ = mJ × 1.000000e-9

Step-by-Step Example

Start with your value in Megajoule. For example: 5 MJ
Multiply by the conversion factor: 5 x 1,000,000,000
The result is: 5,000,000,000 mJ

About Megajoule

The megajoule (MJ) is a unit of energy and work. One megajoule equals 1.000000 × 10^+6 joules. UnitConvertLab converts it against every other energy unit using this exact definition, so results are reproducible to full double precision rather than rounded lookup tables.

Common uses: energy calculations, engineering and science, education.

About Millijoule

The millijoule (mJ) is a unit of energy and work. One millijoule equals 0.001 joules. UnitConvertLab converts it against every other energy unit using this exact definition, so results are reproducible to full double precision rather than rounded lookup tables.

Common uses: energy calculations, engineering and science, education.

Frequently Asked Questions

How many Millijoule are in 1 Megajoule?

There are exactly 1,000,000,000 Millijoule in 1 Megajoule. This means the conversion factor from Megajoule to Millijoule is 1,000,000,000.

What is the formula to convert Megajoule to Millijoule?

The formula to convert Megajoule to Millijoule is: mJ = MJ × 1.000000e+9. For example, to convert 10 Megajoule to Millijoule, you would multiply 10 by 1,000,000,000.

What is a Megajoule?