Converter
Watts to kWh Calculator
The short answer
To convert watts to kWh, multiply watts by hours of use and divide by 1,000. A 1,000W device running 1 hour uses 1 kWh; a 60W device running 10 hours uses 0.6 kWh.
Source: U.S. EIA, July 2026 data · Updated
Watts to kWh formula
kWh = watts × hours ÷ 1,000
Watts measure power — how fast a device uses energy. Kilowatt-hours measure energy — how much it used over time. That’s why you need the hours of use to convert between them.
Common conversions
| Device | Watts | Hours/day | kWh/day | kWh/month |
|---|---|---|---|---|
| Laptop | 60 | 8 | 0.48 | 14.6 |
| TV | 100 | 5 | 0.50 | 15.2 |
| Gaming PC | 500 | 4 | 2.00 | 60.8 |
| Window Air Conditioner | 900 | 8 | 7.20 | 219.0 |
| Space Heater | 1,500 | 8 | 12.00 | 365.0 |
| EV Charger | 7,200 | 2 | 14.40 | 438.0 |
Want the dollar figure for your state? Use the electricity cost calculator or estimate your whole bill with the electric bill estimator.
Sources & method
- Electricity rates: U.S. Energy Information Administration, Electric Power Monthly — average residential retail price, July 2026 (latest available). Retrieved .
- CO₂: EIA State Electricity Profiles, 2024 emissions rate of in-state power generation.
- Formulas, duty cycles and limitations: methodology. Data download: open data (CC BY 4.0).