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Single-Phase RMS Voltage, Current & Real Power

Calculate real electrical power using RMS voltage, RMS current and a supplied power factor.

Calculator inputs

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Enter the known values in the units shown. Results update as you type.
Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
Use the worked example to check the method. Reset restores the starting fields.

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At 120 V RMS, 2 A RMS and power factor 0.8, real power is 192 W. The apparent-power product is 240 VA.

Real power = RMS voltage × RMS current × power factor

Enter these known values and leave the other values blank.

This is a single-phase load model with nonnegative voltage, current and consumed real power. Power factor lies between 0 and 1.
Use RMS values and the applicable true power factor for AC. For a steady DC load use power factor 1; peak AC voltage is not interchangeable with RMS voltage.
For sinusoidal voltage and current, power factor can be written cos φ. With distortion, phase angle alone may not determine true power factor.
No three-phase line/phase conversion is performed. Zero factors can make an inverse calculation non-unique.

They are equal when power factor is 1. For smaller power factor, real power in watts is smaller than apparent power in VA.

No. Three-phase power requires the appropriate line or phase relationships and balance assumptions.

The power unit uses the International Table BTU per hour consistently with the reviewed energy convention.