What is the difference between electrical and mechanical power?

Electrical power (P = IV or P = V²/R) measures the rate at which electrical energy is transferred or dissipated. Mechanical power (P = W/t) measures the rate at which work is done by a force over time. Both are expressed in watts (W).

Which formula should I use?

Use P = IV when you know voltage and current. Use P = V²/R when you know voltage and resistance. Use P = I²R when you know current and resistance. Use P = W/t when you know work (energy) and time elapsed.

A watt (W) is the SI unit of power, defined as one joule of energy per second. One watt of electrical power equals one volt times one ampere (1 W = 1 V × 1 A).

Can I solve for voltage or current instead of power?

Yes. Leave the field you want to find blank and fill in the other fields. The calculator will rearrange the formula and solve for the missing variable.

Does this calculator handle AC circuits?

This calculator computes real (active) power using DC or purely resistive AC assumptions. For AC circuits with reactive components, apparent power (VA) and power factor must also be considered, which is beyond the scope of this tool.

Power Calculator

Select a power formula (P=IV, P=V²/R, P=I²R, or P=W/t) and enter the known values to instantly calculate power in watts or solve for any variable.