⚡ CircuitSecrets
Transformer Rating Calculator
Professional transformer sizing — kW / kVA / HP input, turns ratio, primary & secondary current, standard size matching & loading analysis
kW / kVA / HP
Turns Ratio
FLC Primary
FLC Secondary
Standard Sizes
Loading %
Sizing Tool
Transformer Input
Load Unit
kW
kVA
HP
Load & Power Factor
Transformer Parameters
Sizing Result
Transformer Analysis
Primary
— V
— A
▶
— kVA
▶
Secondary
— V
— A
Recommended Rating
—
Calculate to see result
Standard Size Match
Standard Transformer Sizes
| Rating (kVA) | Required kVA | Loading % | Status |
|---|
► Formulas
Transformer Sizing Method
kVA (from kW) = kW / (PF × η)
kVA (from HP) = HP × 0.746 / (PF × η)
kVA (from kVA) = kVA / η
Design kVA = calculated kVA × safety margin
I_primary = kVA×1000 / (√3 × V_pri) [3-ph]
I_secondary = kVA×1000 / (√3 × V_sec)
Turns Ratio = V_primary / V_secondary
⚠ Note: Transformer sizing includes safety margin for future load growth. Actual transformer ratings follow IEC 60076 standards. Always verify with manufacturer datasheets and consider harmonic loads, starting currents and ambient temperature.
