5 Watts to Joules
Watts measure power and joules measure energy, so the answer depends on time. Here is what a 5 W device uses over each period.
5 J per second
Because 1 watt = 1 joule per second, 5 W delivers 5 J every second it runs.
- Per minute
- 300 J
- Per hour
- 18,000 J
- Per hour (kWh)
- 0.005 kWh
- Per day
- 432,000 J
5 watts to joules, explained
A watt is a rate: one watt means one joule of energy is used every second. So 5 watts means 5 joules per second. To get a total number of joules you multiply by how long the power runs.
For example, a 5 W device left on for one hour uses 5 × 3,600 = 18,000 J. Over a full day it uses 432,000 J. On an electricity bill, one hour of use is 0.005 kWh.
5 W draws about 8.3% of the power of an old-style 60 W incandescent bulb. One hour at 5 W consumes 0.005 kWh of electricity — about 0.075¢ at a US average residential rate of $0.15 per kWh.
joules = 5 W × time in secondsSmartphone charger (5 W)
Standard USB wall chargers draw about 5 watts of active power to top up phone battery packs.
Electrical Power Comparison Scale
Need a different power or time? Use the interactive converter below for any combination.
5 W energy over time
| Time on | Energy (joules) |
|---|---|
| 1 second | 5 J |
| 1 minute | 300 J |
| 10 minutes | 3,000 J |
| 1 hour | 18,000 J |
| 6 hours | 108,000 J |
| 1 day | 432,000 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: 5 watts
How many joules is 5 watts?
5 watts is not a fixed number of joules on its own — watts measure power and joules measure energy, so you need a time. A 5 W device uses 5 J every second, 18,000 J over one hour (0.005 kWh).
How do you convert 5 watts to joules?
Multiply 5 by the number of seconds the power runs. Joules = 5 × time in seconds. For one hour that is 5 × 3,600 = 18,000 J.
How much energy does a 5 W device use per hour?
A 5 W device running for one hour uses 18,000 J, which is 0.005 kWh on an electricity bill.