How many watt hours are in a kilowatt hour?

Exactly 1,000. So 500 Wh is 0.5 kWh, 250 Wh is 0.25 kWh, 100 Wh is 0.1 kWh and 5,000 Wh is 5 kWh. The swap button between the two boxes runs it the other way, where 7.5 kWh is 7,500 Wh and 0.5 kWh is 500 Wh.

What is the formula for Wh to kWh?

kWh = Wh / 1,000, and Wh = kWh x 1,000. Because the divisor is a power of ten, the digits never change: 12,345 Wh is 12.345 kWh and 0.5 Wh is 0.0005 kWh. That also means the conversion is exact in both directions, with no repeating decimal to round, which is not true of the kilojoule and BTU rows in the same list.

Is a kilowatt hour ever 1,024 watt hours?

No. The 1,024 step belongs to digital storage, where kibibytes and kilobytes disagree, and it has no equivalent in energy. Here kilo is the SI prefix and means a thousand exactly, in Wh, kWh and kJ alike. Digital storage is a separate category on this converter, reached from the strip of category buttons above the stage.

My battery is rated in mAh. Can this convert that?

Not on its own, and no converter can. Milliampere hours measure charge, not energy, so the same 5,000 mAh is a different amount of energy at 3.7 volts than at 11.1 volts. The unit list has no mAh row for that reason. Once the label gives you watt hours, which airlines and laptop batteries usually print, this page takes it: 100 Wh is 0.1 kWh.

What is the difference between watts and watt hours?

A watt is a rate of energy use and a watt hour is an amount of energy: one watt drawn for one hour. The conversion here is between amounts, so do the multiplication first and then convert. A 60 watt lamp left on for two hours has used 120 Wh, which this page turns into 0.12 kWh.

Worked example: what else is 1,000 Wh?

1 kWh, and the list restates the same energy as 3,600,000 joules, 3,600 kilojoules, 860,420.650096 calories, 860.420650096 kilocalories and 3,412.14163313 BTU. Half of that, 500 Wh, reads 0.5 kWh, 1,800,000 J, 1,800 kJ and 1,706.07081656 BTU. Each row has its own Copy button, and Copy result above the list copies the headline figure without separators.

How many joules is a watt hour?

3,600 joules, because a watt is a joule per second and an hour is 3,600 seconds. In kilojoules that is 3.6 kJ per watt hour, and in the thermochemical calories this page uses it is 860.420650096 cal or 0.860420650096 kcal. Switch on Show 1 more and the electronvolt row appears as well, where 1 Wh is 2.246943e22 eV.

Will it tell me what a kilowatt hour costs?

No. This page converts the quantity of energy and carries no tariff, standing charge or region, since a rate per kWh changes by supplier and by month. It does the arithmetic that comes before that: read the watt hours off a label or a meter, convert to the unit the bill is written in, and apply your own rate.

Wh to kWh Converter

This is the one conversion on the energy page with nothing to argue about: kilo is the SI prefix for a thousand, so 1,000 Wh is exactly 1 kWh and the answer is the digits you typed with the decimal point moved three places left. 500 Wh is 0.5 kWh, 2,400 Wh is 2.4 kWh, 12,345 Wh is 12.345 kWh and 8 Wh is 0.008 kWh. The page opens with Watt hour in the From box and Kilowatt hour in the To box, ahead of whatever pair the converter last remembered, and the list under the headline carries the same energy in joules, kilojoules, calories, kilocalories and BTU, so 1,000 Wh also reads 3,600,000 J, 3,600 kJ and 3,412.14163313 BTU. Watt hours and watts are not the same quantity, and the converter handles only the first of them: a rating in watts is a rate, so multiply it by the hours it runs before bringing the figure here.

From

To0.001

1 Wh in every energy unit

JouleJ
3,600
KilojoulekJ
3.6
Caloriecal
860.420650096
Kilocaloriekcal
0.860420650096
Kilowatt hourkWh
0.001
British thermal unitBTU
3.41214163313

Common questions

How many watt hours are in a kilowatt hour?: Exactly 1,000. So 500 Wh is 0.5 kWh, 250 Wh is 0.25 kWh, 100 Wh is 0.1 kWh and 5,000 Wh is 5 kWh. The swap button between the two boxes runs it the other way, where 7.5 kWh is 7,500 Wh and 0.5 kWh is 500 Wh.
What is the formula for Wh to kWh?: kWh = Wh / 1,000, and Wh = kWh x 1,000. Because the divisor is a power of ten, the digits never change: 12,345 Wh is 12.345 kWh and 0.5 Wh is 0.0005 kWh. That also means the conversion is exact in both directions, with no repeating decimal to round, which is not true of the kilojoule and BTU rows in the same list.
Is a kilowatt hour ever 1,024 watt hours?: No. The 1,024 step belongs to digital storage, where kibibytes and kilobytes disagree, and it has no equivalent in energy. Here kilo is the SI prefix and means a thousand exactly, in Wh, kWh and kJ alike. Digital storage is a separate category on this converter, reached from the strip of category buttons above the stage.
My battery is rated in mAh. Can this convert that?: Not on its own, and no converter can. Milliampere hours measure charge, not energy, so the same 5,000 mAh is a different amount of energy at 3.7 volts than at 11.1 volts. The unit list has no mAh row for that reason. Once the label gives you watt hours, which airlines and laptop batteries usually print, this page takes it: 100 Wh is 0.1 kWh.
What is the difference between watts and watt hours?: A watt is a rate of energy use and a watt hour is an amount of energy: one watt drawn for one hour. The conversion here is between amounts, so do the multiplication first and then convert. A 60 watt lamp left on for two hours has used 120 Wh, which this page turns into 0.12 kWh.
Worked example: what else is 1,000 Wh?: 1 kWh, and the list restates the same energy as 3,600,000 joules, 3,600 kilojoules, 860,420.650096 calories, 860.420650096 kilocalories and 3,412.14163313 BTU. Half of that, 500 Wh, reads 0.5 kWh, 1,800,000 J, 1,800 kJ and 1,706.07081656 BTU. Each row has its own Copy button, and Copy result above the list copies the headline figure without separators.
How many joules is a watt hour?: 3,600 joules, because a watt is a joule per second and an hour is 3,600 seconds. In kilojoules that is 3.6 kJ per watt hour, and in the thermochemical calories this page uses it is 860.420650096 cal or 0.860420650096 kcal. Switch on Show 1 more and the electronvolt row appears as well, where 1 Wh is 2.246943e22 eV.
Will it tell me what a kilowatt hour costs?: No. This page converts the quantity of energy and carries no tariff, standing charge or region, since a rate per kWh changes by supplier and by month. It does the arithmetic that comes before that: read the watt hours off a label or a meter, convert to the unit the bill is written in, and apply your own rate.

Conversion factors are the exact legal definitions where one exists. An inch is exactly 2.54 cm and a pound exactly 0.45359237 kg, so those conversions are exact rather than approximate. Temperature uses offsets rather than factors, and that is shown in the working.