Watt Hours to Kilowatt Hours Converter

Watt Hours to Kilowatt Hours

Convert watt hours (Wh) to kilowatt hours (kWh). Both measure work and power, and the conversion comes up in nutrition, electricity, fitness work.

The Formula

`` kilowatt hours = watt hours × 0.001 watt hours = kilowatt hours × 1000 `

One watt hour is 0.001 kilowatt hours, and one kilowatt hour is 1,000 watt hours.

Conversion Table

Watt Hours	Kilowatt Hours
1 Wh	0.001 kWh
2 Wh	0.002 kWh
5 Wh	0.005 kWh
10 Wh	0.01 kWh
25 Wh	0.025 kWh
50 Wh	0.05 kWh
100 Wh	0.1 kWh
500 Wh	0.5 kWh
1,000 Wh	1 kWh

The Other Direction

Kilowatt Hours	Watt Hours
1 kWh	1,000 Wh
2 kWh	2,000 Wh
5 kWh	5,000 Wh
10 kWh	10,000 Wh
25 kWh	25,000 Wh
50 kWh	50,000 Wh
100 kWh	100,000 Wh
500 kWh	500,000 Wh
1,000 kWh	1,000,000 Wh

What Each Unit Is

Watt Hours (Wh) — one watt sustained for one hour, or 3,600 joules. The practical electrical energy unit, following the adoption of the watt.

Kilowatt Hours (kWh) — 1,000 watt-hours, or 3.6 million joules. The unit electricity has been billed in since metering began.

A Sense of Scale

• A phone battery holds 12–20 Wh
• A laptop battery is 50–100 Wh
• A home uses 8–30 kWh a day
• An EV takes 15–20 kWh per 100 km

Precision

The factor 0.001 is exact by international agreement, not a rounded approximation. Any imprecision in a result comes from your input, not the conversion.

In Code

`javascript const wattHourToKilowattHour = (value) => value * 0.001; ``

Where This Conversion Comes Up

• Nutrition
• Electricity
• Fitness
• Heating
• Fuel

How Many Decimals Do You Need?

Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 Wh with the factor truncated at each decimal place:

Decimals kept	Factor	137 Wh becomes	Error
0	0	0	100.0000%
1	0	0	100.0000%
2	0	0	100.0000%
3	0.001	0.137	—
4	0.001	0.137	—

A rule that holds for any conversion: round once, at the end. Rounding the factor and then multiplying compounds the error through every subsequent calculation, while carrying full precision and rounding the final answer does not.

The right number of significant figures is set by your input, not by the converter. If you measured watt hours to three significant figures, the answer in kilowatt hours is only good to three — writing more digits claims precision the measurement never had.