Transformers & motors
Transformer kVA Calculator
Transformer-side current equals apparent power divided by voltage. Balanced three-phase current also divides by the square root of three.
Calculate transformer current from kVA and voltage for single-phase or balanced three-phase systems.
Calculated result
Transformer current
Calculating…
Calculated locally in your browser
Planning math only. Verify equipment specifications and installation requirements separately.
What this calculator returns
This is the kVA-current relationship, not a protection or conductor-sizing output.
Formula and variables
The calculation runs entirely in your browser. Static formulas, definitions, examples, and tables remain readable without JavaScript.
I = 1000 × kVA/V (1φ); I = 1000 × kVA/(√3 × VLL) (3φ).
- P
- Real or mechanical power, as identified by the calculator.
- S
- Apparent power in VA or kVA.
- V
- Winding, line, or load voltage.
- I
- Winding, line, or estimated input current.
- PF
- Entered power factor where real and apparent power differ.
- η
- Entered conversion or motor efficiency.
Use the voltage for the transformer side whose current you want.
Worked example
| Input | Value |
|---|---|
| Phase | Three-phase AC |
| Transformer rating | 75 kVA |
| Side voltage | 480 V |
| Result | A 75 kVA, 480 V three-phase side carries about 90.21 A at rated apparent power in the ideal balanced relationship. |
A 75 kVA, 480 V three-phase side carries about 90.21 A at rated apparent power in the ideal balanced relationship.
Reference table
| Apparent rating | 240 V single-phase | 480 V three-phase |
|---|---|---|
| 1 kVA | 4.17 A at 240 V 1φ | 1.20 A at 480 V 3φ |
| 5 kVA | 20.83 A at 240 V 1φ | 6.01 A at 480 V 3φ |
| 10 kVA | 41.67 A at 240 V 1φ | 12.03 A at 480 V 3φ |
| 25 kVA | 104.17 A at 240 V 1φ | 30.07 A at 480 V 3φ |
Frequently asked questions
Is this transformer kVA result code compliant?
No. PowerTotals performs transparent electrical math and planning estimates. Installation decisions must be checked against equipment documentation, the adopted code, and the authority having jurisdiction.
Are my inputs uploaded?
No. Calculations run locally in your browser, and analytics never receives raw electrical values.
Assumptions and limitations
- No impedance, losses, temperature rise, regulation, breaker, fuse, or conductor sizing.
Method and sources
Read the calculation methodology, review the technical sources, or browse the reference table index. Last reviewed .