MihsabaHow to use
kW measures how quickly energy is used; kWh measures the amount used over a period. There is no fixed conversion between them without a running time. Enter power in kilowatts and duration in hours to obtain both kWh and Wh. Divide watts by 1,000 before entering power, and divide minutes by 60 before entering time. For example, a 1,500 W appliance running for 90 minutes is entered as 1.5 kW for 1.5 hours, giving 2.25 kWh. Use measured average power when an appliance cycles on and off.
- Enter Power (kW).
- Enter Running time (hours).
- Calculate and check the result and its unit.
How it is calculated
Example
A constant 2 kW load running for 5 hours uses 10 kWh, or 10,000 Wh. At that same power, each half hour adds 1 kWh.
Important notes
The calculation assumes constant power or an average that represents the entire running period. A maximum nameplate rating is not necessarily continuous consumption for a cycling appliance. If power changes between intervals, calculate each interval and add its energy. This tool calculates energy, not a bill: multiply kWh by your own price per kWh or use the electricity cost calculator.
Worked examples and interpreting results
A constant 2 kW load running for 5 hours uses 10 kWh, or 10,000 Wh. At that same power, each half hour adds 1 kWh.
| Case | Calculation | Result |
|---|---|---|
| Energy | 2 × 5 | 10 kWh |
| In watt-hours | 10 × 1000 | 10,000 Wh |
| 1,500 W for 90 minutes | (1500 ÷ 1000) × (90 ÷ 60) | 2.25 kWh |
How to check the result
The calculation assumes constant power or an average that represents the entire running period. A maximum nameplate rating is not necessarily continuous consumption for a cycling appliance. If power changes between intervals, calculate each interval and add its energy. This tool calculates energy, not a bill: multiply kWh by your own price per kWh or use the electricity cost calculator.
Frequently asked questions
Is 1 kW equal to 1 kWh?
A constant 1 kW used for one hour consumes 1 kWh. Used for three hours, it consumes 3 kWh. Power and energy are different quantities.
How do I enter minutes?
Divide by 60 to get hours: 45 minutes is 0.75 hours and 90 minutes is 1.5 hours.
How do I convert kWh back to kW?
Divide energy by elapsed hours to find average power. For example, 12 kWh over 6 hours gives 2 kW average power.
What if power changes over time?
Calculate and add energy for each interval. One kW for two hours plus three kW for half an hour gives 2 + 1.5 = 3.5 kWh.