Convert Watt-Hour to Kilowatt-Hour (Wh → kWh)

Converting watt-hours to kilowatt-hours is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1. 1
   Take your value in watt-hours

   Start with the number of watt-hours (Wh) you want to convert.
2. 2
   Multiply by 0.001

   The conversion factor from Wh to kWh is 0.001. Multiply your value by this number.
3. 3
   Read the result in kilowatt-hours

   The result is your value in kilowatt-hours (kWh).

Multiply the value in watt-hours by 0.001. For the reverse direction, multiply by 1,000.

• ✓1 Wh = 3600 J = 0.001 kWh.
• ✓Battery mAh × V = Wh. A 3000 mAh phone battery at 3.7 V = 11.1 Wh.
• ✓Airline limits lithium batteries to 100 Wh for carry-on.

• ✗Confusing mAh with Wh — need voltage to convert.
• ✗Using Wh when kWh is more appropriate for large batteries.
• ✗Forgetting the voltage in battery capacity calculations.

What is the Watt-Hour?

The watt-hour equals exactly 3,600 joules and is the standard unit for small-battery capacity, household electrical energy, and renewable-energy storage. A smartphone battery stores roughly 12–15 Wh, a laptop battery 50–100 Wh, and an electric car battery 60,000–100,000 Wh (60–100 kWh). The watt-hour represents the energy delivered by a 1-watt device running for 1 hour. It is the natural unit for connecting power (watts) to time, which is why electric utilities bill in kilowatt-hours. The watt-hour relates to the joule (3,600 J = 1 Wh), the kilowatt-hour (1,000 Wh = 1 kWh), and the BTU (1 Wh ≈ 3.412 BTU). Battery capacity, solar panel output (Wh per day), and energy storage system specifications all rely on the watt-hour as the base small-energy unit.

• Laptop and phone battery capacity
• Portable power banks and UPS
• Home solar panel daily output

What is the Kilowatt-Hour?

The kilowatt-hour equals 1,000 watt-hours (3.6 megajoules) and is the universal billing unit for residential electricity consumption around the world. A typical US household uses about 800–1,000 kWh per month; a refrigerator consumes 1–2 kWh per day, an LED bulb at 10 W for 10 hours uses 0.1 kWh, and a Tesla Model 3 has a 75 kWh battery (about 250–350 miles of range). Electric utility rates are quoted in cents per kWh — typical US residential rates are 11–25 ¢/kWh, while industrial rates are lower. The kilowatt-hour is essential in renewable-energy planning: solar panel output, wind farm production, and grid-scale storage are all rated in kWh or MWh (megawatt-hours). It relates to the watt-hour (1,000 Wh = 1 kWh), the joule (1 kWh = 3.6 MJ), the BTU (1 kWh ≈ 3,412 BTU), and the megawatt-hour (1,000 kWh = 1 MWh).

• Electricity billing globally
• EV battery capacity specifications
• Home solar and battery storage