Power Factor Correction Calculator
Capacitor size needed to correct a load's power factor.
Enter your values
Enter the real power in kW.
Enter the current power factor you are working with.
Enter the target power factor you are working with.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Required capacitor rating
- 55.32 kVAR
- Original apparent power
- 133.33 kVA
- New apparent power
- 105.26 kVA
Quick answer
Required kVAR = P x (tan(cos^-1 pf1) - tan(cos^-1 pf2)).
Qc = P (tan(phi1) - tan(phi2))
At a glance
| What it does | Capacitor size needed to correct a load's power factor. |
|---|---|
| Category | Engineering |
| Inputs needed | Real power, Current power factor, Target power factor |
| Main output | Required capacitor rating |
| Formula | Qc = P (tan(phi1) - tan(phi2)) |
| Cost | Free — no sign-up, no download |
How to use the Power Factor Correction Calculator
- 1Enter the real power drawn by the load.
- 2Enter the current power factor and the target power factor.
- 3Read the capacitor bank size (in kVAR) needed to make the correction.
Inputs explained
- Real power(kW)
- Enter the real power in kW.
- Current power factor
- Enter the current power factor you are working with.
- Target power factor
- Enter the target power factor you are working with.
Worked example
Using the values the calculator loads with:
Inputs
- Real power100 kW
- Current power factor0.75
- Target power factor0.95
Results
- Required capacitor rating55.32 kVAR
- Original apparent power133.33 kVA
- New apparent power105.26 kVA
Frequently asked questions
Why correct power factor?
A higher power factor reduces apparent power draw, cutting utility demand charges and losses.
What causes low power factor?
Inductive loads like motors and transformers are the most common cause in industrial settings.
What do I need to enter into the Power Factor Correction Calculator?
Just 3 values: real power, current power factor, target power factor. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Power Factor Correction Calculator work out the answer?
Required kVAR = P x (tan(cos^-1 pf1) - tan(cos^-1 pf2)). It applies the formula Qc = P (tan(phi1) - tan(phi2)) and shows the working so you can check each step by hand.
Is the Power Factor Correction Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.