Mechanical Power Output Calculator
Power is the rate at which work is done. Enter the work performed in joules and the time taken in seconds to find the mechanical power output in watts, then see it converted to horsepower. This is the basic definition behind engine ratings, athletic power, and machinery specifications: the same total work done in less time means more power.
Power formula
P = W / t
where W = work (J), t = time (s), P = power (W)
Horsepower = P / 745.7 (mechanical hp)
One watt is one joule per second. The mechanical horsepower is defined as 550 foot-pounds per second, which equals approximately 745.7 watts.
Worked example
A motor does 6,000 J of work in 4 seconds. Power = 6,000 / 4 = 1,500.00 W. In horsepower this is 1,500 / 745.7 = 2.01 hp.
Power output: frequently asked questions
What is mechanical power?
Mechanical power is the rate at which work is done or energy is transferred: P = W / t. One watt equals one joule of work done per second.
How do I convert watts to horsepower?
One mechanical horsepower equals 745.7 watts (defined as 550 foot-pounds per second). This calculator divides the power in watts by 745.7 to report horsepower alongside the watt value.
Can I compute power from force and velocity instead?
Yes, in principle: for a constant force moving at constant velocity, P = F * v. If you have work and time, use this calculator directly; if you have force and speed, multiply them, since work over time equals force times distance over time, which is force times velocity.
What units does this calculator use?
Work is entered in joules and time in seconds, giving power in watts. Horsepower is derived using the 745.7 watt mechanical horsepower definition.
Sources
- NIST: SI units (watt, joule, second).
- NIST Special Publication 811: Guide for the Use of the SI (horsepower conversion factor).
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.