Power Calculator – Calculate Power from Work and Time
Calculate power in watts from work done over time. This physics and engineering calculator converts between units and shows horsepower for mechanical applications.
Work and Time
Power Results
Enter work and time to calculate power
Common Power Values
Household Devices:
- LED bulb: 5-15 W
- Laptop: 30-60 W
- Refrigerator: 100-200 W
- Microwave: 800-1200 W
- Electric heater: 1500-2000 W
Mechanical Power:
- Human cycling: 100-200 W
- Electric motor (small): 500-2000 W
- Car engine: 75,000-200,000 W
- 1 horsepower = 745.7 W
How to Calculate Power
Determine Work Done
Find the energy transferred or work completed in joules.
Measure Time
Record how long it took to do the work in seconds.
Divide Work by Time
Power equals work divided by time (P = W/t).
Features
✓Multiple Energy Units
Support for joules, calories, watt-hours, and kilowatt-hours.
✓Time Flexibility
Enter time in seconds, minutes, or hours.
✓Horsepower Conversion
Shows mechanical power in horsepower for engines and motors.
✓Real-World Context
Compares result to common devices and applications.
Frequently Asked Questions
What is power in physics?
Power is the rate of doing work or transferring energy. It measures how fast energy is used. One watt equals one joule per second.
How is power different from energy?
Energy is the capacity to do work. Power is how fast that energy is used. A battery stores energy; power is how quickly it drains.
What is one horsepower?
One horsepower equals 745.7 watts. James Watt defined it as the power a horse could sustain. It's still used for engines and motors.
How do I calculate electrical power?
For electricity: P = V × I (voltage times current). Also P = I²R (current squared times resistance) or P = V²/R.
Why is power important?
Power determines how quickly devices can do work. Higher power means faster acceleration, quicker heating, or brighter lights.