ConverterHub

Power from Work and Time Calculator

Average power from work done over time.

How it is calculated

Average power is work divided by time:

P = W / t

W is the work done in joules (J) and t is the time in seconds (s); the result is in watts (W), where 1 W = 1 J/s. The time must be above zero, since dividing by zero is meaningless. Work may be negative (the result is then a negative power, for example energy taken out of a system). The answer is rounded to two decimals. It is the average over the whole interval, so peaks inside the interval can be higher. When the work is lifting a mass m through a height h, use W = m × g × h with g ≈ 9.81 m/s².

Worked example

A 60 kg person climbs a 3 m flight of stairs in 5 seconds.

  1. Work against gravity: 60 × 9.81 × 3 = 1765.8 J
  2. Power = 1765.8 / 5 = 353.16 W

Climbing the same stairs in 10 s would need half as much power, 176.58 W, although the work is identical.

Try this example →

Common mistakes

  • Entering kilojoules, kilowatt-hours or calories as the work: the field is in joules, and 1 kWh is 3,600,000 J.
  • Entering minutes or hours for the time: it must be in seconds, so 2 minutes is 120.
  • Confusing work with force: a force in newtons is not work until you multiply it by the distance moved.
  • Reading kilograms or weight as work: lifting 60 kg is not 60 J; multiply mass by 9.81 and by the height.

About this calculator

This calculator applies the definition of average mechanical power, P = W / t: the total work done (in joules) divided by the time it took (in seconds), giving a result in watts. Because power is a rate, the same amount of work done twice as fast means twice the power — the calculator lets you see that trade-off directly rather than working the division by hand.

Physics students use it for classic problems like comparing how much power two people generate carrying the same load up a flight of stairs at different speeds, and it's the same relationship engineers use to size motors: knowing the work a machine must perform and the time available tells you the minimum power rating it needs.

Was this helpful?

You can pick up to 3 reactions.

Comments (0)

  • Be the first to comment.

Popular calculators

Loan Calculator

Monthly payment, total interest and full amortization schedule.

Percentage Calculator

Percent change, percent of, and ratio calculations.

Discount Calculator

Calculate final price, savings, and discount amount.

BMI Calculator

Body mass index from height and weight (metric or imperial).

Age Calculator

Compute your exact age in years, months and days from a birth date.

Compound Interest Calculator

Calculate the final amount and interest earned with compounding.

All Calculators