Joules to Kilowatt Hours
An instant joules-to-kilowatt hours converter, with the formula and a reference table below.
| Joules | Kilowatt Hours |
|---|---|
| 1 J | 2.77778e-07 kWh |
| 2 J | 5.55556e-07 kWh |
| 3 J | 8.33333e-07 kWh |
| 5 J | 1.38889e-06 kWh |
| 10 J | 2.77778e-06 kWh |
| 25 J | 6.94444e-06 kWh |
| 50 J | 1.38889e-05 kWh |
| 100 J | 2.77778e-05 kWh |
How to use
- Enter a value in the Joules field.
- The Kilowatt Hours figure appears immediately — no button to press.
- Typing in the Kilowatt Hours field converts back to Joules the same way.
- Use the reference table for the values that come up most often.
Joules to Kilowatt Hours formula
To convert joules to kilowatt hours, multiply by 2.77777778e-07.
kWh = J × 2.77777778e-07
Why this factor: the joule and the kilowatt-hour are both defined against the joule, so dividing one definition by the other gives 2.77777778e-07 directly. Both definitions are set out in full below.
To go the other way, divide by 2.77777778e-07 — or use the Kilowatt Hours to Joules converter, which is the same calculation reversed.
Worked example
Given 500 J, multiplying by 2.77777778e-07 yields 0.000139 kWh.
500 J × 2.77777778e-07 = 0.000139 kWh
The converter above does this for any value you type, in either direction.
What is a joule?
The joule is the SI unit of energy — the work done by one newton acting over one meter.
Definition: Defined as 1 N·m, equivalently one watt-second. Named after James Prescott Joule.
Where it is used: All scientific energy calculations, food energy on European labels, and mechanical work.
What is a kilowatt-hour?
A kilowatt-hour is the standard billing unit for electricity — one kilowatt drawn for one hour.
Definition: Exactly 3.6 megajoules.
Where it is used: Electricity bills worldwide, solar generation figures, and electric vehicle battery capacity.
Joules vs Kilowatt Hours
The joule is an SI unit while the kilowatt-hour is a specialized unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many kilowatt hours are in a joule?
One joule equals 2.77777778e-07 kilowatt hours.
What is the formula to convert joules to kilowatt hours?
Multiply the number of joules by 2.77777778e-07. To reverse it, divide by 2.77777778e-07 instead.
How do I convert kilowatt hours back to joules?
Divide by 2.77777778e-07, which is the same as multiplying by 3600000.
How many kilowatt hours are in 10 joules?
10 J works out to 2.77778e-06 kWh.
How is the joule defined?
Defined as 1 N·m, equivalently one watt-second. Named after James Prescott Joule.