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Watt-hours to kilowatt-hours

Multiply watt-hours by 0.001 to get kilowatt-hours.

1 Wh = 0.001 kWhNIST SP 811
Wh
5kWh

5,000 Wh = 5 kWh

How to convert watt-hours to kilowatt-hours

The kilowatt-hour is one kilowatt for one hour, exactly 3.6 megajoules — the electricity billing unit. The watt-hour is one watt sustained for one hour, exactly 3600 joules — one thousandth of a kilowatt-hour.

Worked example — 5,000 Wh: 5,000 × 0.001 = 5 kWh.

Watt-hours to kilowatt-hours table

Common conversions. The reverse table is on kilowatt-hours to watt-hours.
Watt-hoursKilowatt-hours
100 Wh0.1 kWh
500 Wh0.5 kWh
1,000 Wh1 kWh
2,000 Wh2 kWh
5,000 Wh5 kWh
10,000 Wh10 kWh
20,000 Wh20 kWh
50,000 Wh50 kWh
100,000 Wh100 kWh

Reverse and related

About watt-hours and kilowatt-hours

Watt-hour (Wh)

1 Wh = 0.001 kWh

Definition. One watt sustained for one hour, exactly 3600 joules — one thousandth of a kilowatt-hour

History and origin

The watt-hour is the energy of one watt delivered for one hour, exactly 3600 joules. It is one thousandth of the kilowatt-hour used on electricity bills.

Current use

Watt-hours rate battery capacity — phone, laptop and power-bank batteries are labelled in Wh or mWh.

Source: NIST SP 811, Appendix B; ISO 80000-5 (energy)

Kilowatt-hour (kWh)

1 kWh = 1,000 Wh

Definition. One kilowatt for one hour, exactly 3.6 megajoules — the electricity billing unit

History and origin

The kilowatt-hour is the energy of one kilowatt sustained for one hour, exactly 3.6 megajoules. It became the standard way to bill electricity as power grids spread.

Current use

Kilowatt-hours are the unit on electricity bills and describe the capacity of batteries, including electric-vehicle packs.

Source: NIST SP 811, Appendix B; ISO 80000-5 (energy)

Where people use this

Watt-hours: battery capacity, small appliances. Kilowatt-hours: electricity bills, EV batteries. A 5000 Wh battery is 5 kWh.

How we know this is right
The factor is fixed by the standards that define the units, not chosen — so it is exact, not a measurement:
1 kWh = 1,000 Wh, so 1 Wh = 1 ÷ 1,000 = 0.001 kWh.

Every value is carried to full double precision; the display is rounded.

Both units are defined in NIST SP 811, Appendix B; ISO 80000-5 (energy).

Questions people ask

How many kWh is 1000 Wh?

1000 Wh is exactly 1 kWh.

How many Wh in a kWh?

One kilowatt-hour is 1000 watt-hours.

How big is a phone battery in kWh?

A phone battery is about 10 to 20 Wh, roughly 0.01 to 0.02 kWh.

All watt-hour conversions