Power Calculator
Find power two ways: from work and time using P = W / t, or from voltage and current using P = V x I. Enter any two values and the third is solved.
How to use the power calculator
- Choose mechanical power (work and time) or electrical power (voltage and current).
- Enter any two of the three values and leave the unknown blank.
- Read off the solved power, work, time, voltage or current.
Examples
Mechanical power
W = 1000 J, t = 10 s
P = 100 W
Electrical power
V = 12 V, I = 2 A
P = 24 W
Frequently asked questions
What is the formula for power?
Power is the rate of doing work, P = W / t, where W is work in joules and t is time in seconds. The result is in watts (W).
How is electrical power calculated?
Electrical power is P = V x I, where V is voltage in volts and I is current in amperes. One volt times one ampere gives one watt.
How many values do I need?
Exactly two within a mode. From any two of work, time and power, or any two of voltage, current and power, the third is determined.
How do I convert watts to other units?
One horsepower is about 746 watts and one kilowatt is 1000 watts. This calculator works in base SI units of joules, seconds and watts.
Why can't time be zero?
Power divides work by time, so a zero time would mean dividing by zero, which is undefined and is rejected.
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