Watts to Watt-Hours Calculator
Turn watts and hours into watt-hours (energy), or solve for watts or running time — for appliances, batteries, power stations and solar.
Quick answer
Watt-hours = watts × hours; watts = watt-hours ÷ hours; hours = watt-hours ÷ watts.
- 100 W for 5 hours = 500 Wh (0.5 kWh)
- 1,000 W for 1 hour = 1,000 Wh = 1 kWh — one “unit” on an electricity bill
- A 1,200 Wh battery powering a 60 W load lasts 20 hours before losses
- 2,400 Wh used over 24 hours is an average of 100 W
How this conversion works
Watts vs watt-hours
Watts are power — how fast energy flows right now. Watt-hours are energy — power kept up over time. A 100 W TV running for five hours uses 500 Wh. Electricity bills, batteries, power stations and solar output are all measured in watt-hours or kilowatt-hours, while appliances, panels and inverters are rated in watts. To convert you always need the time.
Watts to watt-hours chart
| Power | 1 hour | 4 hours | 8 hours | 24 hours |
|---|---|---|---|---|
| 10 W | 10 Wh | 40 Wh | 80 Wh | 240 Wh |
| 50 W | 50 Wh | 200 Wh | 400 Wh | 1,200 Wh |
| 100 W | 100 Wh | 400 Wh | 800 Wh | 2,400 Wh |
| 300 W | 300 Wh | 1,200 Wh | 2,400 Wh | 7,200 Wh |
| 500 W | 500 Wh | 2,000 Wh | 4,000 Wh | 12,000 Wh |
| 1,000 W | 1,000 Wh | 4,000 Wh | 8,000 Wh | 24,000 Wh |
| 1,500 W | 1,500 Wh | 6,000 Wh | 12,000 Wh | 36,000 Wh |
| 2,000 W | 2,000 Wh | 8,000 Wh | 16,000 Wh | 48,000 Wh |
How many watt-hours do appliances use?
Typical running watts and hours of use; check your own appliance label. Fridges cycle on and off, so their average draw is far below their running wattage.
| Appliance | Watts | Hours a day | Wh a day | kWh a month |
|---|---|---|---|---|
| Wi-Fi router | 12 W | 24 | 288 Wh | 8.64 |
| LED bulb | 10 W | 6 | 60 Wh | 1.8 |
| Laptop | 60 W | 8 | 480 Wh | 14.4 |
| TV | 100 W | 5 | 500 Wh | 15 |
| Refrigerator (average draw) | 60 W | 24 | 1,440 Wh | 43.2 |
| Desktop PC | 200 W | 6 | 1,200 Wh | 36 |
| Window AC / 1-ton split | 1,000 W | 8 | 8,000 Wh | 240 |
| Space heater | 1,500 W | 4 | 6,000 Wh | 180 |
| Microwave | 1,200 W | 0.25 | 300 Wh | 9 |
Add up the daily watt-hours of everything you want to run, then size panels with the solar power calculator or a battery with the battery runtime calculator.
Frequently asked questions
Multiply watts by the number of hours the device runs. 60 W for 3 hours is 180 Wh.
Divide watt-hours by the hours. 600 Wh used over 4 hours is an average of 150 W.
1,000 Wh, which is 1 kWh — one unit on an electricity bill.
No. A watt is a rate of power; a watt-hour is an amount of energy, equal to one watt sustained for one hour.
About 10 hours before losses (500 ÷ 50); in practice 8–9 hours after inverter losses of 10–15%.
Electrical unit converters
- Watts to amps calculator
- Amps to watts calculator
- Watts to kilowatts calculator
- kW to kVA calculator
- Ohm's law calculator
- Ah to Wh calculator
- Ah to kWh calculator
- Amp-hours to amps calculator
- kWh to mAh calculator
- Joules to watts calculator
- HP to kW calculator
- BTU to kW calculator
- kWh to MJ calculator
- AWG to mm² calculator
Learn more
Sources & standards
The watt and watt-hour follow SI definitions from NIST: one watt-hour is one watt sustained for one hour (3,600 joules).
- NIST Special Publication 811 — Guide for the Use of the International System of Units (SI) — National Institute of Standards and Technology
Defines the watt, watt-hour, ampere and the conversion factors used on this page.