Select time, power, or energy and enter the two known quantities. Use constant or interval-average power; watts alone cannot determine seconds. Units include kW, mechanical hp, min, h, Wh, and kWh.
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Watts To Seconds Formula
For constant or interval-average power, E = P × t relates energy, power, and time. To find seconds from energy and watts, rearrange it as t = E ÷ P; to find power, use P = E ÷ t.
Variables:
- E is the energy (joules)
- P is the power (watts)
- t is the time (seconds)
To calculate the energy, multiply the power in watts by the time in seconds. The result will be the energy in joules. Use constant or interval-average power. For varying power, energy is the integral of power over time.
| Power (W) | Time (s) |
|---|---|
| 5 | 200 |
| 10 | 100 |
| 20 | 50 |
| 25 | 40 |
| 50 | 20 |
| 60 | 16.667 |
| 75 | 13.333 |
| 100 | 10 |
| 150 | 6.667 |
| 200 | 5 |
| 250 | 4 |
| 300 | 3.333 |
| 500 | 2 |
| 750 | 1.333 |
| 1000 | 1 |
| 1500 | 0.667 |
| 2000 | 0.5 |
| 2500 | 0.4 |
| 3000 | 0.333 |
| 5000 | 0.2 |
| *Assumes energy E = 1 kilojoule (1 kJ = 1000 J). Time (s) = Energy (J) ÷ Power (W) = 1000 ÷ P. For reference: 1 kW = 1000 W, 1 mechanical hp ≈ 745.69987158 W. | |
What Does “Watts to Seconds” Mean?
Watts to seconds is not a direct conversion as they measure two different things. A watt is a unit of power in the International System of Units (SI) that measures the rate of energy conversion or transfer, typically used to quantify the rate of energy transfer in electrical systems. On the other hand, seconds measure time. However, when you multiply watts by seconds, you get a measure of energy, expressed in joules (1 watt-second equals 1 joule). This is often used in physics and engineering to calculate energy consumption or production over a specific period of time.
How to Calculate Watts To Seconds?
The following steps find elapsed time from a known energy and constant or average power using t = E ÷ P.
- First, determine the power (P) in watts.
- Next, determine the transferred energy (E) in joules.
- Use t = E ÷ P to calculate elapsed time in seconds. The power must be positive for this inverse calculation.
- Check that energy and power describe the same transfer and interval.
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
power (P) in watts = 50
energy (E) in joules = 500; elapsed time t = 500 J ÷ 50 W = 10 seconds. Equivalently, 50 W × 10 s = 500 J.
