Power consumption calculator
Convert watts and runtime into Wh and kWh, with optional cost at your energy rate.
Power (W)
Hours of use
Price per kWh (optional)
Result
Energy: 800 Wh
Energy: 0.8 kWh
Cost: 0.12
How to use
1. Enter device wattage and hours of use.
2. Optionally add price per kWh.
3. Read Wh, kWh, and estimated cost.
Example
Power consumption calculator
Convert watts and runtime into Wh and kWh, with optional cost at your energy rate.
When to use
• When you need a quick estimate without spreadsheets.
• When you want privacy — calculations stay on your device.
Limitations
• When you need certified engineering or legal calculations.
• When site-specific conditions require a professional survey.
About this calculator
Convert watts and runtime into Wh and kWh, with optional cost at your energy rate.
Questions fréquentes
Is my data uploaded?
No. All math runs locally in your browser.
Is this tool free?
Yes. No account or subscription required.