Power Calculator
Inputs
Enter parameters to calculate Power, Work, or Time.
What is Power?
Power is the rate at which work is done or energy is transferred. In other words, it measures how fast you can do work.
Lifting a heavy box slowly requires the same amount of work as lifting it quickly. However, lifting it quickly requires more power.
The Power Formula
The most common formula for power is work divided by time:
P = W / tAlternatively, since Work is Force × Distance:
P = F × v- P = Power (Watts, W)
- W = Work (Joules, J)
- t = Time (Seconds, s)
- F = Force (Newtons, N)
- v = Velocity (m/s)
Understanding the Watt
The standard unit of power is the Watt (W), named after James Watt. One Watt is equal to one Joule of work done per second.
Another common unit is Horsepower (hp). 1 mechanical horsepower ≈ 746 Watts. This unit is often used for engines and motors.
Examples
Example 1: Climbing Stairs
You weigh 700 N and climb 3 meters of stairs in 5 seconds. Work done = 700 × 3 = 2100 J.
- Work (W) = 2100 J
- Time (t) = 5 s
- Power = 2100 / 5 = 420 Watts
Example 2: Car Engine
A car engine exerts 2000 N force to keep the car moving at 30 m/s.
- Force (F) = 2000 N
- Velocity (v) = 30 m/s
- Power = 2000 × 30 = 60,000 W = 60 kW (approx 80 hp)
Frequently Asked Questions
Is electrical power different?
Not really. In electricity, Power = Voltage × Current (P=VI), but the unit is still Watts. It still represents the rate of energy transfer.
What is a Kilowatt-hour (kWh)?
It's actually a unit of Energy, not Power. It's the amount of energy used if you run a 1,000 Watt device for 1 hour. (1 kW × 1 h).
How do I convert Watts to Horsepower?
Divide the Watts by 746. For example, 1500 W / 746 ≈ 2 hp.