Transformer Turns Ratio Calculator

About this calculator

This calculator finds a transformer's secondary voltage and current from its turns ratio: Vs/Vp = Ns/Np, and by conservation of power, Is/Ip = Np/Ns. Given the primary voltage, the primary or secondary turns count (or the ratio itself), it returns the induced secondary voltage and the resulting current under the ideal-transformer assumption.

Electrical engineers, electricians, and electronics students use it when selecting a step-up or step-down transformer for a power supply, choosing tap settings on a distribution transformer, or checking a design against a datasheet's rated voltages. It's a quick way to confirm whether a transformer will deliver the voltage a circuit needs.