Generator Power Calculator
Calculate generator output power, apparent power, and power factor
Volts (V) - RMS for AC
Amperes (A) - RMS for AC
0.1 to 1.0 (1.0 for resistive loads)
How to Use This Calculator
Enter Voltage
Enter the generator output voltage in volts (RMS for AC).
Enter Current
Enter the generator output current in amperes (RMS for AC).
Set Power Factor
Enter power factor (0-1). Use 1.0 for resistive loads, 0.8-0.9 for motors.
Get Results
Click calculate to see real power (W or kW) and apparent power (VA or kVA).
Formula
P = V × I × PF
S = V × I
Where:
- P = Real power (Watts)
- S = Apparent power (VA)
- V = Voltage (Volts, RMS)
- I = Current (Amperes, RMS)
- PF = Power factor (0 to 1)
Example:
Voltage = 240 V, Current = 10 A, Power Factor = 0.9
P = 240 × 10 × 0.9 = 2,160 W (2.16 kW)
S = 240 × 10 = 2,400 VA (2.4 kVA)
About Generator Power Calculator
The Generator Power Calculator helps calculate generator output power. It determines real power (active power) and apparent power based on voltage, current, and power factor. This is essential for generator sizing and understanding power delivery.
When to Use This Calculator
- Generator Sizing: Determine required generator size for loads
- Power Analysis: Analyze generator output and efficiency
- Load Planning: Plan electrical loads for generator capacity
- Educational Purposes: Learn about power calculations
Why Use Our Calculator?
- ✅ Accurate Calculations: Uses correct power formulas
- ✅ Dual Output: Shows both real and apparent power
- ✅ Easy to Use: Simple interface
- ✅ Free Tool: No registration required
Common Applications
Backup Power: Calculate generator size needed for home or business backup power based on connected loads.
Construction Sites: Size portable generators for construction equipment and tools.
Tips for Accurate Results
- Use RMS values for AC voltage and current
- Power factor is 1.0 for resistive loads, 0.8-0.9 for motors
- Generator rating is typically in kVA (apparent power)
- Consider starting surge current for motor loads
Frequently Asked Questions
What's the difference between real and apparent power?
Real power (W) is the actual power doing work. Apparent power (VA) is the product of voltage and current. For resistive loads, they're equal. For reactive loads, apparent power is higher than real power.
Why is generator rating in kVA?
Generators are rated in kVA (apparent power) because they must supply both real and reactive power. The kVA rating indicates the maximum apparent power the generator can deliver.
How do I size a generator?
Add up all load powers, account for power factor, and add 20-30% margin for starting surges and future expansion. The generator kVA rating should exceed the total kVA requirement.