Power factor
0.8108
Free power triangle tool
Power Factor Calculator
Calculate power factor, kW, kVA, kVAR, phase angle, and estimated current from practical electrical input pairs.
Electrical power triangle
Power factor inputs
Real, apparent, reactive, and current
Quick examples
Phase angle
35.825 degrees
Real power
15 kW
Apparent power
18.5 kVA
Reactive power
10.8282 kVAR
Current
26.7024 A
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What is a power factor calculator?
A power factor calculator helps you work through the relationship between real power in kW, apparent power in kVA, reactive power in kVAR, and power factor. In practical electrical work, this matters whenever you need to understand how efficiently a load is using supplied power.
This tool is useful for motors, drives, distribution planning, generator checks, load studies, and electrical troubleshooting where you need to calculate missing values in the power triangle or estimate current from voltage and phase type.
Instead of only returning the power factor number, this calculator also shows the phase angle, real power, apparent power, reactive power, and estimated current so the result is more useful for actual decision-making.
Why power factor matters in real electrical systems
Power factor describes how much of the supplied apparent power is doing real useful work. A load with a lower power factor can draw more current for the same real power, which can affect conductor loading, system losses, voltage drop, equipment sizing, and utility costs.
This is especially important with inductive equipment like motors, transformers, and some electronic loads, where reactive power becomes part of the full electrical picture even though it is not converted directly into useful output.
Low power factor can increase current
More current may be needed to deliver the same real power when power factor drops.
Apparent power is not the same as real power
kVA includes the full electrical demand, while kW is the working portion.
Reactive power changes the picture
kVAR helps explain why current and apparent demand can rise without equal useful work output.
System planning depends on the full power triangle
Sizing and analysis are more accurate when real, reactive, and apparent power are all considered together.
How the power factor formulas work
The most important relationship is:
Core formula
Power factor = Real power / Apparent power
The rest of the power triangle follows from the same geometry. If you know two of the key values, the others can usually be solved. Reactive power comes from the right-triangle relationship between kW, kVA, and kVAR, while phase angle is derived from the cosine relationship behind power factor.
Step 1: Start with a supported pair of known values
Use real and apparent power, real and reactive power, or apparent power plus power factor.
Step 2: Solve the rest of the power triangle
The calculator fills in the missing kW, kVA, kVAR, and phase angle values.
Step 3: Estimate current when voltage is known
Current is derived from apparent power, supply voltage, and whether the load is single-phase or three-phase.
Step 4: Use the result for practical load understanding
The outputs help explain how the load behaves, not just what one single number means.
Quick reference examples for power factor work
These examples show common ways electricians and planners may approach the power triangle.
| Known values | What you can solve |
|---|---|
| 15 kW and 18.5 kVA | Power factor, reactive power, angle, and current if voltage is known. |
| 10 kW and 7.5 kVAR | Apparent power, power factor, angle, and current if voltage is known. |
| 5 kVA at PF 0.8 | Real power, reactive power, angle, and current if voltage is known. |
| Three-phase voltage plus kVA | Estimated line current for distribution planning. |
| Single-phase voltage plus kVA | Estimated current for smaller load checks and comparisons. |
How to use this power factor calculator
- 1
Choose the right input mode
Start with the pair of values you already know, such as kW and kVA or kVA and power factor.
- 2
Select single-phase or three-phase
This matters when current is estimated from apparent power and voltage.
- 3
Enter voltage if you want current
Voltage is optional for current estimation but not needed to solve the rest of the power triangle.
- 4
Review the full result, not just the PF number
The kW, kVA, kVAR, angle, and current values together give the more useful picture.
- 5
Use the result for planning or troubleshooting
The calculator is best used to understand load behavior, compare equipment demand, or sanity-check measured values.
Real-world uses, edge cases, and limitations
Useful for motors and inductive loads
Helpful when checking why current demand may be higher than simple kW alone suggests.
Useful for current estimation
Apparent power and voltage together give a practical current estimate for load planning.
Useful for understanding load behavior
The power triangle explains how real work, reactive demand, and total electrical demand fit together.
Not a full harmonics or correction study
This calculator does not model harmonics, capacitor-bank tuning, distortion power factor, or detailed system correction design.
Frequently asked questions
- What is power factor?
- Power factor is the ratio of real power to apparent power.
- Why is low power factor a problem?
- Lower power factor can increase current demand, losses, and system loading for the same useful power output.
- What is the difference between kW, kVA, and kVAR?
- kW is real working power, kVA is total apparent demand, and kVAR is reactive power.
- Can this calculator estimate current?
- Yes, if you provide a valid voltage and choose the correct phase type.
Solve the power triangle with practical outputs
Use this power factor calculator to move between kW, kVA, kVAR, power factor, phase angle, and current in one place, so the result is useful for real load checks instead of just a single ratio.