10 Watts to Joules
Watts measure power and joules measure energy, so the answer depends on time. Here is what a 10 W device uses over each period.
10 J per second
Because 1 watt = 1 joule per second, 10 W delivers 10 J every second it runs.
- Per minute
- 600 J
- Per hour
- 36,000 J
- Per hour (kWh)
- 0.01 kWh
- Per day
- 864,000 J
10 watts to joules, explained
A watt is a rate: one watt means one joule of energy is used every second. So 10 watts means 10 joules per second. To get a total number of joules you multiply by how long the power runs.
For example, a 10 W device left on for one hour uses 10 × 3,600 = 36,000 J. Over a full day it uses 864,000 J. On an electricity bill, one hour of use is 0.01 kWh.
10 W draws about 17% of the power of an old-style 60 W incandescent bulb. One hour at 10 W consumes 0.01 kWh of electricity — about 0.15¢ at a US average residential rate of $0.15 per kWh.
joules = 10 W × time in secondsEfficient LED light bulb (10 W)
Modern LED bulbs draw only 10 watts of power while matching the brightness of an obsolete 60-watt incandescent.
Electrical Power Comparison Scale
Need a different power or time? Use the interactive converter below for any combination.
10 W energy over time
| Time on | Energy (joules) |
|---|---|
| 1 second | 10 J |
| 1 minute | 600 J |
| 10 minutes | 6,000 J |
| 1 hour | 36,000 J |
| 6 hours | 216,000 J |
| 1 day | 864,000 J |
Convert any wattage and time
The full Watts to Joules converter handles W, kW, MW, any time unit, and the reverse joules→watts and time calculations.
FAQ: 10 watts
How many joules is 10 watts?
10 watts is not a fixed number of joules on its own — watts measure power and joules measure energy, so you need a time. A 10 W device uses 10 J every second, 36,000 J over one hour (0.01 kWh).
How do you convert 10 watts to joules?
Multiply 10 by the number of seconds the power runs. Joules = 10 × time in seconds. For one hour that is 10 × 3,600 = 36,000 J.
How much energy does a 10 W device use per hour?
A 10 W device running for one hour uses 36,000 J, which is 0.01 kWh on an electricity bill.