Amps to kVA Calculator
Enter current, voltage and phase to calculate apparent power in kVA instantly. Supports both single-phase and three-phase circuits.
How do you convert amps to kVA?
For single-phase, multiply amps by volts and divide by 1000: kVA = (A × V) ÷ 1000. For example, 40 A at 230 V single-phase = (40 × 230) ÷ 1000 = 9.2 kVA. For three-phase, include the √3 factor: kVA = (√3 × A × V) ÷ 1000 ≈ (1.7321 × A × V) ÷ 1000.
Amps to kVA Reference Table
| Current (A) | Single-phase 120 V | Single-phase 230 V | Three-phase 230 V | Three-phase 400 V |
|---|---|---|---|---|
| 10 A | 1.20 kVA | 2.30 kVA | 3.98 kVA | 6.93 kVA |
| 20 A | 2.40 kVA | 4.60 kVA | 7.97 kVA | 13.86 kVA |
| 32 A | 3.84 kVA | 7.36 kVA | 12.75 kVA | 22.17 kVA |
| 40 A | 4.80 kVA | 9.20 kVA | 15.94 kVA | 27.71 kVA |
| 63 A | 7.56 kVA | 14.49 kVA | 25.11 kVA | 43.65 kVA |
| 100 A | 12.00 kVA | 23.00 kVA | 39.84 kVA | 69.28 kVA |
Formula
Three-phase: kVA = (√3 × A × V) ÷ 1,000
Where: A = line current in amps, V = line-to-line voltage in volts, √3 ≈ 1.7321 (three-phase factor), kVA = apparent power in kilovolt-amps.
Note: no power factor is needed because kVA is the apparent power, which is derived solely from voltage and current without needing to know PF. To find real power (kW), multiply kVA by PF.
Commercial Panel Sizing: Amps to Apparent Power
In commercial and industrial electrical work, main service panels and transformers are rated in kVA, but the branch circuits and main breakers are rated in Amps. Converting from the main breaker size to kVA tells you the maximum apparent power the panel can handle:
- 200 A Residential Service (120/240 V Single-Phase):
kVA = (200 × 240) ÷ 1,000 = 48 kVA. This is the theoretical maximum capacity of a standard modern home electrical service. - 225 A Commercial Panel (120/208 V Three-Phase):
kVA = (225 × 208 × 1.732) ÷ 1,000 = 81 kVA. Common in light commercial buildings, restaurants, and retail spaces. - 400 A Industrial Service (277/480 V Three-Phase):
kVA = (400 × 480 × 1.732) ÷ 1,000 = 332 kVA. Used for heavy machinery, large HVAC rooftop units, and manufacturing.
Frequently Asked Questions
Multiply amps by volts, then divide by 1000: kVA = (A × V) ÷ 1000. For 40 A at 230 V: kVA = (40 × 230) ÷ 1000 = 9.2 kVA.
Include the √3 factor: kVA = (√3 × A × V) ÷ 1000. For 100 A at 400 V: kVA = (1.7321 × 100 × 400) ÷ 1000 ≈ 69.28 kVA. V is the line-to-line voltage.
No. kVA (apparent power) is defined as S = V × I and does not require knowledge of power factor. PF is only needed when converting kVA to real power (kW = kVA × PF).
In a balanced three-phase system, the total apparent power is the sum of three phasors displaced by 120°. The resulting scalar relationship between line voltage, line current and total power includes the √3 (≈1.7321) factor, which is fundamental to three-phase AC circuit analysis.
Why is a 3-phase 208V panel rated differently than a 240V single-phase panel?
Three-phase power utilizes three alternating currents offset in time. The formula for 3-phase power includes a √3 (1.732) multiplier. A 100A 3-phase 208V panel provides 36 kVA, whereas a 100A single-phase 240V panel provides only 24 kVA, even though the breaker says 100A in both cases.