Kilowatt-hours to JoulesFree online conversion calculator — instant results, no sign-up
Convert kilowatt-hours to joules and back.
About the Kilowatt-hours to Joules
The Kilowatt-hours to Joules calculator converts energy measured in kilowatt-hours (kWh) into joules (J) and shows the reverse unit relationship. With the default input of 1 kWh, it returns 3,600,000 joules. Its reverse relationship may display 0 kWh because of rounding, not because a joule contains no energy.
- Value in kWh (kWh)
- The energy quantity to convert, measured in kilowatt-hours (kWh), with a default value of 1.
Formula and method
E_J = E_kWh × 3,600,000; reverse conversion: E_kWh = E_J ÷ 3,600,000.
- E_JEnergy in joules (J).
- E_kWhEnergy in kilowatt-hours (kWh).
Multiply the entered kilowatt-hour value by 3,600,000 to obtain joules. This factor follows from 1 kilowatt = 1,000 watts, 1 hour = 3,600 seconds, and 1 watt = 1 joule per second. For the default input, 1 × 3,600,000 = 3,600,000 joules. To convert joules back to kilowatt-hours, divide by the same factor.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Value in kWh1 kWh
Results
- joules3,600,000
- 1 kWh =3,600,000 joules
- 1 joules =0 kWh
How to use the Kilowatt-hours to Joules
- 1Enter the energy amount in the Value in kWh (kWh) field, or leave the default value of 1.
- 2Read the joules result calculated by multiplying the input by 3,600,000.
- 3For the default input, confirm that the result is joules = 3,600,000.
- 4Read the forward relationship row, 1 kWh = = 3,600,000 joules, as the unit conversion factor.
- 5Check the reverse relationship row with rounding in mind; for a precise reverse conversion, divide the joule amount by 3,600,000.
Reading your result
The output joules = 3,600,000 is the converted energy for the default input of 1 kWh. The row 1 kWh = = 3,600,000 joules states the exact forward unit relationship; the repeated equals sign is only display formatting. The row 1 joules = = 0 kWh shows the reverse relationship at insufficient display precision: mathematically, 1 joule equals 1/3,600,000 kWh, approximately 0.000000277778 kWh, rather than zero.
Limitations
The conversion factor is exact, but displayed results may be rounded, especially for small kilowatt-hour quantities in the reverse relationship. The listed input accepts kilowatt-hours; the reverse formula explains how to convert joules back without implying that a separate joule input is available. This tool converts energy units only: it does not calculate power, electricity cost, or losses during energy transfer.
Common questions
Why does 1 kWh equal 3,600,000 joules?+
A kilowatt is 1,000 joules per second, and an hour contains 3,600 seconds. Multiplying 1,000 by 3,600 gives 3,600,000 joules per kilowatt-hour.
Why does the reverse row show 1 joules = = 0 kWh?+
The reverse value is too small for the displayed precision. The exact value is 1/3,600,000 kWh, approximately 0.000000277778 kWh; the displayed zero is a rounding effect.
How do I convert the default joule result back to kilowatt-hours?+
Divide 3,600,000 joules by 3,600,000 joules per kilowatt-hour. The result is 1 kWh, matching the default input.
Can I enter kilowatts instead of kilowatt-hours?+
No. Kilowatts measure power, while kilowatt-hours and joules measure energy. If you know constant power in kilowatts, first multiply it by the operating time in hours to obtain kilowatt-hours.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
Further reading
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Results are estimates for informational purposes and are not financial, medical or legal advice.