45 Watts to Joules
Watts measure power and joules measure energy, so the answer depends on time. Here is what a 45 W device uses over each period.
45 J per second
Because 1 watt = 1 joule per second, 45 W delivers 45 J every second it runs.
- Per minute
- 2,700 J
- Per hour
- 162,000 J
- Per hour (kWh)
- 0.045 kWh
- Per day
- 3,888,000 J
45 watts to joules, explained
A watt is a rate: one watt means one joule of energy is used every second. So 45 watts means 45 joules per second. To get a total number of joules you multiply by how long the power runs.
For example, a 45 W device left on for one hour uses 45 × 3,600 = 162,000 J. Over a full day it uses 3,888,000 J. On an electricity bill, one hour of use is 0.045 kWh.
45 W draws about 75% of the power of an old-style 60 W incandescent bulb. One hour at 45 W consumes 0.045 kWh of electricity — about 0.68¢ at a US average residential rate of $0.15 per kWh.
joules = 45 W × time in secondsStandard business laptop (45 W)
Standard corporate laptops draw about 45 watts when active and charging their internal batteries.
Electrical Power Comparison Scale
Need a different power or time? Use the interactive converter below for any combination.
45 W energy over time
| Time on | Energy (joules) |
|---|---|
| 1 second | 45 J |
| 1 minute | 2,700 J |
| 10 minutes | 27,000 J |
| 1 hour | 162,000 J |
| 6 hours | 972,000 J |
| 1 day | 3,888,000 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: 45 watts
How many joules is 45 watts?
45 watts is not a fixed number of joules on its own — watts measure power and joules measure energy, so you need a time. A 45 W device uses 45 J every second, 162,000 J over one hour (0.045 kWh).
How do you convert 45 watts to joules?
Multiply 45 by the number of seconds the power runs. Joules = 45 × time in seconds. For one hour that is 45 × 3,600 = 162,000 J.
How much energy does a 45 W device use per hour?
A 45 W device running for one hour uses 162,000 J, which is 0.045 kWh on an electricity bill.