Power Factor Calculator

Compare real and apparent power to calculate power factor. Enter your own values below to see power factor and check the method behind it.

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Your inputs

Change the example values to match your situation.

Your result

Let’s work it out.

Fill in your inputs and select Calculate.
Your result and breakdown will appear here.

How this calculator works

Power factor = real power (W) ÷ apparent power (VA).

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What is Power Factor Calculator?

Power Factor Calculator helps you compare real and apparent power to calculate power factor.

The main result is power factor, with a breakdown of power factor percentage. The formula, example and assumptions below explain how to interpret it.

How to use Power Factor Calculator

Use the example to get familiar with the form, then enter your own figures. Any rates in the example are illustrative. Check the field labels and units before calculating.

  1. Gather real power (W) and apparent power (VA). Use values from the same situation or reporting period.
  2. Replace the example real power with your own value, then complete the other fields. Check the displayed units.
  3. Select Calculate and read power factor with its result breakdown. Change one input and calculate again to compare a second scenario. Reset restores the original example.
  • Enter real power in W, at least 0. Decimals are accepted.
  • Enter apparent power in VA, at least 0.000001. Decimals are accepted.

Power Factor Calculator: a worked example

With the inputs below, the result is 0.8 (power factor). Follow the example, then replace these illustrative values with your own.

Example inputs and output
Input or outputExample value
Real power (W)800 W
Apparent power (VA)1,000 VA
Power factor0.8
Power factor percentage80 %

Understanding the Power Factor result

Read power factor alongside power factor percentage. These describe different parts of the same calculation.

Displayed results use a readable number of decimal places. When checking a result by hand, keep extra precision until the last step. To compare scenarios, change one input at a time and keep the others fixed.

  • Example Power factor percentage: 80 %

Power Factor Calculator: assumptions and common mistakes

A useful estimate starts with the right inputs. Check the following assumptions and limits before applying the result to your situation.

  • DC, single-phase and three-phase calculations use different relationships. Equipment selection also depends on installation conditions and applicable standards.

For wider guidance, visit Bureau of Indian Standards. The formula and scope of this specific tool are stated on this page.

Power Factor Calculator FAQs

What does Power Factor Calculator calculate?

Power Factor Calculator helps you compare real and apparent power to calculate power factor. Its main output is power factor.

What inputs do I need for Power Factor Calculator?

You need real power (W) and apparent power (VA). Use the field labels and units to match your figures to the formula.

Which formula does Power Factor Calculator use?

Power factor = real power (W) ÷ apparent power (VA).

What is a worked example for Power Factor Calculator?

Example inputs: Real power: 800 W; Apparent power: 1,000 VA. The result is 0.8 (power factor).

How should I enter real power?

Enter real power in W, at least 0. Decimals are accepted.

How do I choose apparent power?

Enter apparent power in VA, at least 0.000001. Decimals are accepted. The example uses 1,000 VA; replace it if your circumstances differ.

How should I read power factor?

Read power factor alongside power factor percentage. These describe different parts of the same calculation.

Why might my Power Factor Calculator result differ from my records?

DC, single-phase and three-phase calculations use different relationships. Equipment selection also depends on installation conditions and applicable standards. Differences in entered values, units or rounding can also change the comparison.

Can I compare two scenarios in Power Factor Calculator?

Yes. Note your first power factor, change real power or another input, and select Calculate again. Editing a field clears the old result so it is not mistaken for a new calculation.

Is Power Factor Calculator free, and where are my inputs calculated?

This calculator is free to use without signing in. Its formula runs in your browser; calculator inputs are not sent to a calculation API. The inputs reset to the example values when you reset the form or start a fresh page.