120 Watts to Joules
Watts measure power and joules measure energy, so the answer depends on time. Here is what a 120 W device uses over each period.
120 J per second
Because 1 watt = 1 joule per second, 120 W delivers 120 J every second it runs.
- Per minute
- 7,200 J
- Per hour
- 432,000 J
- Per hour (kWh)
- 0.12 kWh
- Per day
- 10,368,000 J
120 watts to joules, explained
A watt is a rate: one watt means one joule of energy is used every second. So 120 watts means 120 joules per second. To get a total number of joules you multiply by how long the power runs.
For example, a 120 W device left on for one hour uses 120 × 3,600 = 432,000 J. Over a full day it uses 10,368,000 J. On an electricity bill, one hour of use is 0.12 kWh.
joules = 120 W × time in secondsNeed a different power or time? Use the interactive converter below for any combination.
120 W energy over time
| Time on | Energy (joules) |
|---|---|
| 1 second | 120 J |
| 1 minute | 7,200 J |
| 10 minutes | 72,000 J |
| 1 hour | 432,000 J |
| 6 hours | 2,592,000 J |
| 1 day | 10,368,000 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.
Frequently asked questions
How many joules is 120 watts?
120 watts is not a fixed number of joules on its own — watts measure power and joules measure energy, so you need a time. A 120 W device uses 120 J every second, 432,000 J over one hour (0.12 kWh).
How do you convert 120 watts to joules?
Multiply 120 by the number of seconds the power runs. Joules = 120 × time in seconds. For one hour that is 120 × 3,600 = 432,000 J.
How much energy does a 120 W device use per hour?
A 120 W device running for one hour uses 432,000 J, which is 0.12 kWh on an electricity bill.