30 Watts to Joules
Watts measure power and joules measure energy, so the answer depends on time. Here is what a 30 W device uses over each period.
30 J per second
Because 1 watt = 1 joule per second, 30 W delivers 30 J every second it runs.
- Per minute
- 1,800 J
- Per hour
- 108,000 J
- Per hour (kWh)
- 0.03 kWh
- Per day
- 2,592,000 J
30 watts to joules, explained
A watt is a rate: one watt means one joule of energy is used every second. So 30 watts means 30 joules per second. To get a total number of joules you multiply by how long the power runs.
For example, a 30 W device left on for one hour uses 30 × 3,600 = 108,000 J. Over a full day it uses 2,592,000 J. On an electricity bill, one hour of use is 0.03 kWh.
30 W draws about 50% of the power of an old-style 60 W incandescent bulb. One hour at 30 W consumes 0.03 kWh of electricity — about 0.45¢ at a US average residential rate of $0.15 per kWh.
joules = 30 W × time in secondsCeiling fan (medium) (30 W)
A standard ceiling fan draws around 30 watts on its medium speed setting.
Electrical Power Comparison Scale
Need a different power or time? Use the interactive converter below for any combination.
30 W energy over time
| Time on | Energy (joules) |
|---|---|
| 1 second | 30 J |
| 1 minute | 1,800 J |
| 10 minutes | 18,000 J |
| 1 hour | 108,000 J |
| 6 hours | 648,000 J |
| 1 day | 2,592,000 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: 30 watts
How many joules is 30 watts?
30 watts is not a fixed number of joules on its own — watts measure power and joules measure energy, so you need a time. A 30 W device uses 30 J every second, 108,000 J over one hour (0.03 kWh).
How do you convert 30 watts to joules?
Multiply 30 by the number of seconds the power runs. Joules = 30 × time in seconds. For one hour that is 30 × 3,600 = 108,000 J.
How much energy does a 30 W device use per hour?
A 30 W device running for one hour uses 108,000 J, which is 0.03 kWh on an electricity bill.