Physics

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kVA Calculator.

Calculate single-phase apparent power from RMS voltage and current.

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Results update as you type.

Apparent power: 2.4 kVA

Apparent power

0.000000kVA
Apparent power: 2,400 VA

Apparent power

0.000000VA

Results update automatically as you type.

Use Cases

Sizing electrical equipment

Determine the apparent power rating needed for transformers, generators, or UPS systems in single-phase applications.

Example: A 230 V circuit with 10 A current requires 2.3 kVA.

Educational reference

Students and engineers can quickly verify apparent power calculations for single-phase AC circuits.

Example: Check that 120 V × 5 A = 0.6 kVA.

Frequently Asked Questions

What is apparent power in kVA?
Apparent power (S) in kVA is the product of RMS voltage (V) and RMS current (A) divided by 1000. It represents the total power in an AC circuit, including both real and reactive power.
How do I use this kVA calculator?
Enter the RMS voltage in volts and the RMS current in amperes into the respective fields. The calculator will compute the apparent power in kilovolt-amperes (kVA) using the formula S(kVA) = V(V) × I(A) / 1000.
Is this calculator for single-phase or three-phase?
This calculator is specifically for single-phase circuits. For three-phase, you would need a different formula that includes the square root of 3.

Tips & Common Mistakes

Tips

  • Ensure you use RMS values, not peak values, for accurate results.
  • For single-phase circuits, the formula is simple: multiply volts by amps and divide by 1000.
  • If you have power factor and real power, you can derive kVA, but this calculator only uses voltage and current.

Common Mistakes to Avoid

  • Using peak voltage or current instead of RMS values, which leads to overestimation.
  • Forgetting to divide by 1000 to convert from VA to kVA.
  • Applying this single-phase formula to three-phase systems without adjustment.

Last updated: August 13, 2026