Millijoule to Watt-Hour Converter

Energy Converter

27 units available

Decimals:

From

To

2.777778e-7

1 mJ = 2.777778e-7 Wh

Formula:

Wh = mJ × 2.777778e-7

With your value: 1 mJ = 2.777778e-7 Wh

How big is that?

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

Your value1.00 mJ

Heartbeat (1.0e+3× your value)1.00e+3 mJ

AA battery charge (1.0e+7× your value)1.00e+7 mJ

Slice of bread (2.8e+8× your value)2.80e+8 mJ

Daily food intake (8.4e+9× your value)8.40e+9 mJ

Litre of petrol (3.4e+10× your value)3.42e+10 mJ

Other Millijoule to Watt-Hour conversions

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

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

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

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.

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

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

How to Convert Millijoule to Watt-Hour

To convert from Millijoule (mJ) to Watt-Hour (Wh), multiply the value by 2.777778e-7.

Formula: Wh = mJ × 2.777778e-7

Reverse: mJ = Wh × 3,600,000

Step-by-Step Example

Start with your value in Millijoule. For example: 5 mJ
Multiply by the conversion factor: 5 x 2.777778e-7
The result is: 1.388889e-6 Wh

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.

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.

Frequently Asked Questions

How many Watt-Hour are in 1 Millijoule?

There are exactly 2.777778e-7 Watt-Hour in 1 Millijoule. This means the conversion factor from Millijoule to Watt-Hour is 2.777778e-7.

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

The formula to convert Millijoule to Watt-Hour is: Wh = mJ × 2.777778e-7. For example, to convert 10 Millijoule to Watt-Hour, you would multiply 10 by 2.777778e-7.

What is a Millijoule?