Watt-Hour to Millijoule Converter

Energy Converter

27 units available

Decimals:

From

To

3,600,000

1 Wh = 3,600,000 mJ

Formula:

mJ = Wh × 3,600,000

With your value: 1 Wh = 3,600,000 mJ

How big is that?

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

Heartbeat (1/3.6e+3 your value)0.000278 Wh

Your value1.00 Wh

AA battery charge (2.8× your value)2.78 Wh

Slice of bread (78× your value)77.8 Wh

Daily food intake (2.3e+3× your value)2.33e+3 Wh

Litre of petrol (9.5e+3× your value)9.50e+3 Wh

Other Watt-Hour to Millijoule conversions

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

Watt-Hour to Millijoule Conversion Table

Watt-Hour (Wh)	Millijoule (mJ)
0.5	1,800,000
1	3,600,000
2	7,200,000
5	18,000,000
10	36,000,000
15	54,000,000
20	72,000,000
25	90,000,000
50	180,000,000
100	360,000,000
250	900,000,000
500	1,800,000,000
1000	3,600,000,000

Millijoule to Watt-Hour Conversion Table

Millijoule (mJ)	Watt-Hour (Wh)
0.5	1.388889e-7
1	2.777778e-7
2	5.555556e-7
5	1.388889e-6
10	2.777778e-6
15	4.166667e-6
20	5.555556e-6
25	6.944444e-6
50	1.388889e-5
100	2.777778e-5
250	6.944444e-5
500	0.000139
1000	0.000278

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.

Watt-Hour (Wh)

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 Watt-Hour to Millijoule

To convert from Watt-Hour (Wh) to Millijoule (mJ), multiply the value by 3,600,000.

Formula: mJ = Wh × 3,600,000

Reverse: Wh = mJ × 2.777778e-7

Step-by-Step Example

Start with your value in Watt-Hour. For example: 5 Wh
Multiply by the conversion factor: 5 x 3,600,000
The result is: 18,000,000 mJ

About Watt-Hour

The watt-hour (Wh) is a unit of energy and work. One watt-hour equals 3600 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 Watt-Hour?

There are exactly 3,600,000 Millijoule in 1 Watt-Hour. This means the conversion factor from Watt-Hour to Millijoule is 3,600,000.

What is the formula to convert Watt-Hour to Millijoule?

The formula to convert Watt-Hour to Millijoule is: mJ = Wh × 3,600,000. For example, to convert 10 Watt-Hour to Millijoule, you would multiply 10 by 3,600,000.

What is a Watt-Hour?