kW to kWh Calculator
Enter power in kilowatts (kW) and runtime to calculate energy in kilowatt-hours (kWh).
What this calculator does
This tool converts power usage (kW) into energy consumption (kWh). If you are trying to estimate a utility bill, compare appliances, or understand EV charging usage, this is the conversion you need.
Power and energy are related, but not the same:
- kW (kilowatt) = how fast electricity is being used right now.
- kWh (kilowatt-hour) = total electricity used over time.
kW to kWh formula
The conversion is straightforward:
If runtime includes minutes, convert minutes to decimal hours first:
Quick examples
| Power | Runtime | Energy Used |
|---|---|---|
| 1.0 kW | 5 hours | 5.0 kWh |
| 2.4 kW | 2.5 hours | 6.0 kWh |
| 0.75 kW | 45 minutes (0.75 h) | 0.5625 kWh |
How to use the calculator correctly
- Enter the device or load rating in kW. If your label is in watts, divide by 1000 first (e.g., 1500 W = 1.5 kW).
- Enter total runtime in hours and optional minutes.
- Optionally enter your utility rate to estimate cost.
- If this usage repeats daily, add days per month to get a monthly estimate.
Common appliances and typical power ratings
Actual values vary by model and operating mode, but these ranges can help with planning:
- Space heater: 1.0 to 1.5 kW
- Electric oven: 2.0 to 3.5 kW
- Window AC: 0.5 to 1.5 kW
- EV charger (Level 2): 3.3 to 11 kW+
- Laptop charger: 0.045 to 0.1 kW
Billing estimate (optional)
Once you know kWh, cost is easy:
Example: If you use 8 kWh and your rate is $0.16/kWh, your estimated cost is $1.28.
Frequently asked questions
Is 1 kW for 1 hour always 1 kWh?
Yes. That is the exact definition of a kilowatt-hour.
Can I convert kWh back to kW?
Yes, if you know time. Rearranged formula: kW = kWh ÷ hours.
Why does my bill not match exactly?
Utilities may include tiered rates, taxes, fees, time-of-use pricing, or demand charges. This calculator gives a clean engineering estimate.
Bottom line
For any electrical load, kW tells you the instantaneous draw, and kWh tells you what you actually consumed. Use this calculator to make fast, accurate conversions and to estimate operating cost with confidence.