300 Watts to Joules
Watts measure power and joules measure energy, so the answer depends on time. Here is what a 300 W device uses over each period.
300 J per second
Because 1 watt = 1 joule per second, 300 W delivers 300 J every second it runs.
- Per minute
- 18,000 J
- Per hour
- 1,080,000 J
- Per hour (kWh)
- 0.3 kWh
- Per day
- 25,920,000 J
300 watts to joules, explained
A watt is a rate: one watt means one joule of energy is used every second. So 300 watts means 300 joules per second. To get a total number of joules you multiply by how long the power runs.
For example, a 300 W device left on for one hour uses 300 × 3,600 = 1,080,000 J. Over a full day it uses 25,920,000 J. On an electricity bill, one hour of use is 0.3 kWh.
300 W draws about the same power as 5 old-style 60 W incandescent bulbs running at once. One hour at 300 W consumes 0.3 kWh of electricity — about $0.045 at a US average residential rate of $0.15 per kWh.
joules = 300 W × time in secondsNext-gen gaming console (active) (300 W)
A console draws 300 watts of electrical power when rendering heavy 4K HDR 3D graphics.
Electrical Power Comparison Scale
Need a different power or time? Use the interactive converter below for any combination.
300 W energy over time
| Time on | Energy (joules) |
|---|---|
| 1 second | 300 J |
| 1 minute | 18,000 J |
| 10 minutes | 180,000 J |
| 1 hour | 1,080,000 J |
| 6 hours | 6,480,000 J |
| 1 day | 25,920,000 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: 300 watts
How many joules is 300 watts?
300 watts is not a fixed number of joules on its own — watts measure power and joules measure energy, so you need a time. A 300 W device uses 300 J every second, 1,080,000 J over one hour (0.3 kWh).
How do you convert 300 watts to joules?
Multiply 300 by the number of seconds the power runs. Joules = 300 × time in seconds. For one hour that is 300 × 3,600 = 1,080,000 J.
How much energy does a 300 W device use per hour?
A 300 W device running for one hour uses 1,080,000 J, which is 0.3 kWh on an electricity bill.