MihsabaConvert energy units, power or electricity costs?
kW measures power while kWh measures energy used over time. You cannot turn a power rating into energy consumption without a running duration.
Use this converter for: Changing between energy units such as kWh, joules, Wh, calories and BTU. For example 1 kWh equals 3,600,000 joules.
- Convert kW and operating hours to kWh — An appliance rated 2 kW running for 5 hours uses 10 kWh. Include the time period.
- Estimate a kWh price or appliance running cost — Combine energy consumption with the price per kWh to estimate daily or monthly cost.
- Convert watts to kilowatts — Divide watts by 1,000 to change W to kW. This converts power, not energy.
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How to use
Convert energy units used in physics, electricity and heat through the joule as a common base. The tool includes J, kJ, MJ, Wh, kWh, thermochemical calories, kilocalories, BTU, electronvolts and foot-pounds. Converting power in kW to energy in kWh requires running time in hours: 2 kW for 5 hours gives 10 kWh. This converter changes energy units; use the kW to kWh calculator when your inputs are power and time.
- Enter the energy amount and source unit.
- Choose the target unit.
- Read the converted value plus quick equivalents in joules, kWh, kcal and BTU.
How it is calculated
Example
Example: 1 kWh = 3,600,000 J ≈ 860.4206501 kcal ≈ 3,412.141633 BTU. A kilowatt-hour is energy; a kilowatt by itself is power, not energy.
Important notes
The cal and kcal units here use the thermochemical definition: 1 cal = 4.184 J and 1 kcal = 4,184 J. A food-label Calorie usually means one kilocalorie. Energy cannot be converted to power without a time interval because power = energy ÷ time.
Worked examples and interpreting results
One kilowatt-hour equals 3600000 joules. Its name combines power and time, but it is an energy unit. One kilojoule is 1000 joules, regardless of device or material.
| Case | Calculation | Result |
|---|---|---|
| Kilowatt-hour to joules | 1000 W × 3600 s | 3,600,000 J |
| Kilojoule to joules | 1 × 1000 | 1,000 J |
How to check the result
Converting between energy and power requires time; kWh and kW are not equivalent. When using calories, check cal versus kcal and the selected definition: a kilocalorie is a thousand calories.
Convert joules and kilowatt-hours
One kilowatt-hour equals exactly 3.6 million joules, while one watt-hour equals 3,600 joules. These conversion factors connect kWh, MJ, kJ and Wh.
- 1 kWh to MJ: 3600000 / 1000000 = 3.6 MJ
- 500 Wh to MJ: 500 × 3600 / 1000000 = 1.8 MJ
- 2000 J to kJ: 2000 / 1000 = 2 kJ
Important note
kW measures power, not energy. Converting kW into kWh also requires the operating time.
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Frequently asked questions
How many joules are in 1 kWh?
Exactly 3,600,000 joules.
Is a kcal the same as a food Calorie?
In nutrition, a capital-C Calorie usually means one kilocalorie, equal to 4,184 J.
Can kWh be converted directly to kW?
No. kWh is energy and kW is power; a time interval is required.
How do I convert kW to kWh?
Multiply kilowatts by running hours. Divide watts by 1,000 and minutes by 60 first if needed. A constant 1,500 W load for 90 minutes uses 2.25 kWh.