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Kilowatt-hours to Joules

Kilowatt-hours (kWh) to joules (J).

Result3,600,000J

Precision (significant figures)

Formula

J = kWh × 3,600,000

1 kWh = 3,600,000 J

J = kWh × 3,600,000 exactly. A kilowatt-hour is 1,000 watts for 3,600 seconds, so 1 kWh is 3.6 MJ and a 30 kWh daily household use is 108 MJ. It's the bridge between electricity bills and physics.

Formula

J = kWh × 3,600,000

Worked example

  1. Start with 1 kWh.
  2. Multiply by 3,600,000 (J per kWh): 1 × 3,600,000 = 3,600,000 J.

Kwh to joules chart

Kilowatt-hours (kWh)Joules (J)
0.0013,600
0.0136,000
0.1360,000
0.51,800,000
13,600,000
27,200,000
518,000,000
1036,000,000
13.548,600,000
30108,000,000
50180,000,000
75270,000,000
100360,000,000
5001,800,000,000
1,0003,600,000,000
10,00036,000,000,000

When you need this conversion

Comparing electricity with gas, fuel or food energy, physics and engineering homework, battery storage and EV specs, and energy audits.

Quick reference

  • 0.5 kWh = 1.8 MJ
  • 1 kWh = 3.6 MJ
  • 10 kWh = 36 MJ
  • 30 kWh = 108 MJ
  • 100 kWh = 360 MJ

Energy vs power

kWh measures energy; kW measures power. A 2 kW heater running for 3 hours uses 6 kWh, which is 21.6 MJ. For power ratings, see horsepower to kilowatts.

Comparing fuels

Natural gas is often billed in therms (29.3 kWh each) or cubic meters (about 10.5–11 kWh each, depending on the supplier’s calorific value). Converting everything to kWh or MJ puts bills on the same footing.

Common mistakes

Writing kW/h. The unit is kilowatt-hour (kWh), a product, not a rate.

Forgetting the 1,000. 1 Wh is 3,600 J; 1 kWh is 3,600,000 J.

For food energy, see kcal to kJ.

Questions

How many joules is 1 kWh?

3,600,000 J, or 3.6 MJ.

How many kWh is 1 MJ?

0.277778 kWh.

How much energy is in a 10 kWh battery?

36 MJ.

How many kWh in a therm?

29.3071 kWh.

Sources

Last reviewed 2026-09-24. How we check values · Report a problem with this page