kVA Calculator
Calculate kilovolt-amperes (kVA) apparent power for electrical systems
Calculate Apparent Power (kVA)
System voltage
Load current
Electrical Power Results
Formula used: S = I × V / 1000
System type: Single-phase AC system
Power Analysis
Example Calculations
Single-Phase Example
System: Single-phase transformer
Voltage: 240 V
Current: 10 A
Formula: S = I × V / 1000
Calculation
S = 10 A × 240 V / 1000
S = 2400 VA / 1000
S = 2.4 kVA
With PF = 0.85: P = 2.4 × 0.85 = 2.04 kW
3-Phase Example
Same voltage and current in 3-phase line-to-line:
S = √3 × 10 A × 240 V / 1000
S = 1.732 × 2400 / 1000
S = 4.16 kVA
Common kVA Ratings
Residential
5-25 kVA
Whole house backup
Small Commercial
25-100 kVA
Small businesses
Industrial
100+ kVA
Manufacturing plants
Utility Scale
1000+ kVA (1+ MVA)
Power substations
Power Factor Guide
1.0 = Unity power factor (ideal, resistive load)
0.9-1.0 = Excellent (most residential loads)
0.8-0.9 = Good (standard commercial)
0.7-0.8 = Fair (needs improvement)
<0.7 = Poor (requires correction)
0.0 = Purely reactive (capacitive/inductive)
Understanding kVA and Electrical Power
What is kVA?
kVA (kilovolt-amperes) is the unit of apparent power in electrical systems. It represents the total power flowing in a circuit, combining both real power (kW) that does useful work and reactive power (kVAR) that is stored and released by reactive components.
kVA vs kW
- •kVA: Apparent power (total power flow)
- •kW: Real power (actual work done)
- •kVAR: Reactive power (stored/released)
- •Relationship: kVA² = kW² + kVAR²
Power Formulas
Single Phase: S = I × V / 1000
3-Phase (L-L): S = √3 × I × V(L-L) / 1000
3-Phase (L-N): S = 3 × I × V(L-N) / 1000
Power Factor Relationships
PF = cos(θ) = P / S
P (kW) = S (kVA) × PF
Q (kVAR) = S (kVA) × sin(θ)
Note: Generators and transformers are typically rated in kVA because their thermal limits depend on current, regardless of power factor.