Wh to MJ Converter

How to convert watt-hours to megajoules

FormulaMJ = Wh × 0.0036

Multiply the value in watt-hours by 0.0036. To go the other way, multiply by 277.7777778 (or divide by 0.0036).

A watt-hour is smaller than a megajoule: it takes 277.7777778 watt-hours to make one megajoule.

Worked examples

1 watt-hour1 Wh × 0.0036 = 0.0036 MJ
5 watt-hours5 Wh × 0.0036 = 0.018 MJ
10 watt-hours10 Wh × 0.0036 = 0.036 MJ
20 watt-hours20 Wh × 0.0036 = 0.072 MJ
100 watt-hours100 Wh × 0.0036 = 0.36 MJ

Watt-hours to megajoules conversion table

Values are calculated by the conversion engine and rounded to 8 significant figures.

Watt-hours to megajoules: 0.1–10 Wh
Watt-hours (Wh)	Megajoules (MJ)
0.1 Wh	0.00036 MJ
0.25 Wh	0.0009 MJ
0.5 Wh	0.0018 MJ
1 Wh	0.0036 MJ
2 Wh	0.0072 MJ
3 Wh	0.0108 MJ
4 Wh	0.0144 MJ
5 Wh	0.018 MJ
6 Wh	0.0216 MJ
7 Wh	0.0252 MJ
8 Wh	0.0288 MJ
9 Wh	0.0324 MJ
10 Wh	0.036 MJ

Watt-hours to megajoules: 12–1,000 Wh
Watt-hours (Wh)	Megajoules (MJ)
12 Wh	0.0432 MJ
15 Wh	0.054 MJ
20 Wh	0.072 MJ
25 Wh	0.09 MJ
30 Wh	0.108 MJ
40 Wh	0.144 MJ
50 Wh	0.18 MJ
75 Wh	0.27 MJ
100 Wh	0.36 MJ
250 Wh	0.9 MJ
500 Wh	1.8 MJ
1,000 Wh	3.6 MJ

About the units

Watt-hour (Wh)

One watt sustained for an hour: 3,600 J. Battery capacities are rated in Wh.

Megajoule (MJ)

The megajoule (MJ) is a unit of energy in the International System of Units (SI). One megajoule equals 1,000,000 joules (J).

Frequently asked questions

How many megajoules are in one watt-hour?

There are 0.0036 megajoules in one watt-hour, and this value is exact by definition.

How do I convert watt-hours to megajoules?

Multiply the number of watt-hours by 0.0036. For example, 10 Wh × 0.0036 = 0.036 MJ.

How many watt-hours are in one megajoule?

One megajoule equals 277.7777778 watt-hours. That is the reverse factor, 1 ÷ 0.0036.

What is 10 watt-hours in megajoules?

10 Wh = 0.036 MJ.

Is this Wh to MJ converter accurate?

Yes. Both units are defined exactly in terms of SI units, so the conversion factor is exact; results are shown to 12 significant figures by default and you can change precision in the converter. Calculations run in your browser using the same tested engine that generated this page.