Mechanical power calculator
Power, work or time from P = W ÷ t.
Fill in the fields and the result will appear here automatically.
Relate mechanical work to elapsed time: find average power, duration, or work at constant average power. Use it to compare lifting rates and energy transfer. One watt is one joule per second; power is not stored energy. The result is not a motor’s electrical input power because losses and efficiency are not inputs.
How it works
Formula and logic
Pavg = W/t; t = W/P; W = Pavg t. This is the average over an interval; varying power requires integration over time. Metric horsepower uses 1 PS = 735.49875 W. Signed force work can be negative in general, but this interface calculates a nonnegative amount of transferred energy.
Example
1000 J in 10 s gives P = 100 W = 0.136 metric horsepower. The same work in 20 s gives 50 W. Inverse modes: 600 J at 50 W take 12 s; 75 W over 4 s transfer 300 J.
Fields and units
- What to find — list option
- Work — J
- Time — s
- Work — J
- Power — W
- Power — W
- Time — s
How to use
- — Choose power, time or work and enter the two known quantities.
- — Use joules, seconds and watts: multiply minutes by 60 and kilojoules by 1000.
- — Work and power are nonnegative here. Power and work modes require positive duration; zero power cannot determine duration.
Method and limitations
- Calculation method
- Formula and logic
- Data or methodology source
- OpenStax: average power as work over a time interval NIST: metric and mechanical horsepower
- Limitation
- Average nonnegative mechanical power. Efficiency, peak loading and electrical supply power are not calculated.
FAQ
Is this instantaneous motor power?
No. W/t gives average power over the interval. Peak or instantaneous power can differ.
Can I use lifting work from mgh?
Yes, as ideal useful work. Dividing by time gives average useful power; motor input power additionally needs efficiency.
Why can zero watts not determine time?
Nonzero work cannot be completed in finite time at zero power. With zero work and zero power, time is still undetermined: 0/0 does not give an answer.
Is metric horsepower identical to mechanical hp?
No. This tool uses metric horsepower: 735.49875 W. Mechanical hp is about 745.6999 W. Thus 100 W is about 0.136 metric horsepower. Check which unit a specification uses before comparing equipment ratings.