# Power Factor Calculation

**URL:** <https://forumautomation.com/t/power-factor-calculation/14452>\
**Category:** Electrical\
**Tags:** calculator\
**Created:** [September 28, 2026, 7:46am UTC](https://forumautomation.com/t/power-factor-calculation/14452 "2026-09-28T07:46:41Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Rabert](https://forumautomation.com/user_avatar/forumautomation.com/rabert/32/6784_2.png) [@Rabert](https://forumautomation.com/u/Rabert)\
**Post date:** [September 28, 2026, 7:46am UTC](https://forumautomation.com/t/power-factor-calculation/14452/1 "2026-09-28T07:46:41Z")

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**Power Factor (PF) = Real Power (kW) ÷ Apparent Power (kVA)**

For a sinusoidal AC system, **PF = cos φ** , where φ is the phase angle between voltage and current.

A lower power factor requires higher current to deliver the same kW load at the same voltage, increasing equipment loading and I²R losses. FORMULA:

Power Factor (PF) = kW ÷ kVA

Where: • kW = Real Power • kVA = Apparent Power • PF = Power Factor

EXAMPLE:

 ![1](https://cdn.forumautomation.com/original/2X/c/cf4645b1e55f75e8f3750fafd97dea9ef9af4c2b.jpeg)

Real Power = 800 kW Apparent Power = 1000 kVA

PF = 800 ÷ 1000 = 0.80

RESULT: Power Factor = 0.80

Another relation:

PF = cos φ

where φ is the phase angle between voltage and current.

KEY POINT: A lower power factor generally means higher current for the same kW load, which can affect cable, transformer, and switchgear loading.

Lower PF means **higher current for the same real power (kW)** at a given voltage. This can increase loading and losses in cables, transformers, and switchgear.

For modern systems with harmonics, **true power factor** can also include the effect of waveform distortion, so PF is not always simply equal to cos φ.