Home /Calculators /Transformer Turns Ratio

Transformer Turns Ratio

Calculate the turns ratio of a transformer from primary and secondary voltages. Also determines secondary current based on primary current (assuming an ideal transformer with no losses). Identifies whether the configuration is step-up, step-down, or isolation (1:1). Fundamental for AC power supply design.

Primary turns Np

Secondary turns Ns

Primary voltage (V)

Secondary load (W)

Transformer

Turns ratio (Np:Ns)5.00 : 1

TypeStep-down

Secondary voltage46 V

Secondary current2.174 A

Primary current (ideal)434.8 mA

Formulas used

Turns Ratio = Np/Ns = Vp/Vs · Is = Ip × (Np/Ns)

How to use this calculator

Step-by-Step Instructions

Enter primary voltage The voltage applied to the transformer input (e.g., 220V or 120V mains).
Enter secondary voltage The desired output voltage (e.g., 12V, 24V, 48V).
Optionally enter primary current If known, this allows calculation of secondary current and apparent power (VA).
Click Calculate The turns ratio, transformer type (step-up/step-down), and current/power values are displayed.

Worked Example

Vp = 220V, Vs = 12V Turns Ratio = 220/12 = 18.33:1 Step-Down

With Ip = 0.1A Is = 0.1 × 18.33 = 1.83A| Power = 22VA