Power factor calculator
Calculate the power factor (PF) in an alternating current (AC) circuit by providing values for real power (P) and apparent power (S). The power factor indicates the efficiency of power usage in an AC system. This calculator uses the formula PF = P / S. Obtain accurate results for power factor using this convenient online tool, which is useful for analyzing and improving the power efficiency of electrical systems.
What is Power factor calculator
A power factor calculator is a tool that helps you calculate the power factor (PF) of an electrical circuit based on the apparent power (S) and the real power (P) or based on the reactive power (Q) and the apparent power.
The power factor represents the ratio of real power to apparent power and indicates how effectively electrical power is being utilized in a circuit. It is usually expressed as a decimal between 0 and 1 or as a percentage between 0% and 100%.
Here are the formulas for calculating power factor using different parameters:

Power Factor (PF) = Real Power (P) / Apparent Power (S) This formula is used when you know the real power and the apparent power of the circuit.

Power Factor (PF) = Cosine(ฮธ) This formula is used when you know the angle (ฮธ) between the real and apparent power vectors. The cosine of the angle is equal to the power factor.

Power Factor (PF) = Real Power (P) / Square Root of [(Real Power (P))^2 + (Reactive Power (Q))^2] This formula is used when you know the real power and the reactive power of the circuit.
To use a power factor calculator, you typically input the known values (real power, apparent power, and/or reactive power) into the appropriate fields or boxes, and the calculator will compute the power factor value for you. Some calculators may also provide additional features like graphical representation or the ability to convert power factor between decimal and percentage form.
Using a power factor calculator can help you analyze the efficiency of electrical systems and make adjustments to improve power factor and overall power utilization.
Single phase circuit calculation
Power factor calculation:
PF = cos ฯ = 1000 ร P_{(kW)} / (V_{(V)} ร I_{(A)})
Apparent power calculation:
S_{(kVA)} = V_{(V)} ร I_{(A)} / 1000
Reactive power calculation:
Q_{(kVAR)} = โ(S_{(kVA)}^{2}  P_{(kW)}^{2})
Power factor correction capacitor's capacitance calculation:
S_{corrected (kVA)} = P_{(kW)} / PF_{corrected}
Q_{corrected (kVAR)} = โ(S_{corrected (kVA)}^{2}  P_{(kW)}^{2})
Q_{c (kVAR)} = Q_{(kVAR)}  Q_{corrected (kVAR)}
C_{(F)} = 1000 ร Q_{c (kVAR)} / (2ฯf_{(Hz)}รV_{(V)}^{2})
Three phase circuit calculation
For three phase with balanced loads:
Calculation with line to line voltage
Power factor calculation:
PF = cos ฯ = 1000 ร P_{(kW)} / (โ3 ร V_{LL(V)} ร I_{(A)})
Apparent power calculation:
S_{(kVA)} = โ3 ร V_{LL(V)} ร I_{(A)} / 1000
Reactive power calculation:
Q_{(kVAR)} = โ(S_{(kVA)}^{2}  P_{(kW)}^{2})
Power factor correction capacitor's capacitance calculation:
Q_{c (kVAR)} = Q_{(kVAR)}  Q_{corrected (kVAR)}
C_{(F)} = 1000 ร Q_{c (kVAR)} / (2ฯf_{(Hz)}รV_{LL(V)}^{2})
Calculation with line to neutral voltage
Power factor calculation:
PF = cos ฯ = 1000 ร P_{(kW)} / (3 ร V_{LN(V)} ร I_{(A)})
Apparent power calculation:
S_{(kVA)} = 3 ร V_{LN(V)} ร I_{(A)} / 1000
Reactive power calculation:
Q_{(kVAR)} = โ(S_{(kVA)}^{2}  P_{(kW)}^{2})
Power factor correction capacitor's capacitance calculation:
Q_{c (kVAR)} = Q_{(kVAR)}  Q_{corrected (kVAR)}
C_{(F)} = 1000 ร Q_{c (kVAR)} / (3ร2ฯf_{(Hz)}รV_{LN(V)}^{2})
Power factor calculator Example
To calculate the power factor (PF) of an electrical circuit, you need to know the real power (P) and the apparent power (S). The formula to calculate power factor is:
PF = P / S
Here's an example that demonstrates using the power factor formula:
Let's assume we have a circuit with a real power of 500 watts and an apparent power of 600 voltamps. We want to calculate the power factor.
Using the power factor formula: PF = P / S PF = 500 W / 600 VA PF โ 0.83
Therefore, the power factor of the circuit is approximately 0.83.
The power factor is a measure of the efficiency or quality of an electrical system. It represents the ratio between the real power (P) and the apparent power (S). A power factor of 1 (or 100%) indicates a purely resistive load with maximum efficiency, while a power factor less than 1 indicates the presence of reactive power in the system.