Watts to Joules Calculator
Convert Watts to Joules with the formula, a worked example and a table of typical values. Working shown step by step.
Try your own numbers
Estimate only. Not engineering or safety advice. Check the result against the applicable standard and the equipment data, and have a competent engineer review it before it is relied on. Terms of use.
Open in the calculator with these values
Formula
Worked example
| Input | Value |
|---|---|
| Power | 100 W |
| Time | 10 s |
- E = P × t = 100 W × 10 s = 1,000 J
- In other units: 0.000278 kWh = 0.001 MJ; 0.1 kW; 0.002778 h
Typical values
| Time (s) | Energy (J) |
|---|---|
| 1 | 100 |
| 10 | 1,000 |
| 60 | 6,000 |
| 600 | 60,000 |
| 3,600 | 360,000 |
Other inputs are the same as in the worked example above.
Assumptions
- Constant power over the whole time
- Real (active) power, not apparent power
Change any unit to read the answer in kWh, Wh, kJ or MJ. For a varying load the result is the average power or the total energy, not the instantaneous value. For a cost, use Energy and Cost.
Frequently asked questions
How do I convert Watts to Joules?
E = P × t (1 W × 1 s = 1 J, 1 kW × 1 h = 1 kWh = 3.6 MJ). Worked example: Power 100 W, time 10 s gives 1,000 J.
What do I need to enter?
Enter power, energy and time. Leave blank the value you want to find, and the form solves for it. Change the unit of a value with its selector and the result stays the same.
How are watts and joules related?
One watt is one joule per second, so energy in joules is power in watts multiplied by time in seconds.
How accurate are the results?
Every figure comes from the same tested engine as the Elecmetric calculators and is meant for estimating. Check design values against the standard and the equipment data you work to.
Related
Next steps in a design: kWh to kWEnergy ConsumptionEnergy Unit Converter
Opposite direction: Joules to Watts
Also see: Joules to Volts Volts to Joules kW to Wh Wh to kW
Formula guides: Energy ConverterJ to kWh ConverterEnergy and Cost Formulas: kWh and Payback
All 78 conversionsWatts, Joules, kWh and Time (any two) in Elecmetric