Transformer Turns Ratio Calculator

About this calculator

This calculator finds a transformer's secondary voltage and turns ratio using Vs = Vp·(Ns/Np), the ideal-transformer relationship stating that voltage scales directly with the ratio of secondary to primary winding turns. A transformer with more secondary turns than primary turns steps voltage up (used, for example, at power plants to send electricity efficiently over long transmission lines), while fewer secondary turns steps voltage down (used in the transformers that reduce grid voltage to safe levels for homes and electronics).

Electrical engineers use this when designing power distribution equipment and specifying transformers for a given voltage conversion; electricians use it to verify transformer ratings match a job's requirements; and students studying electromagnetism or power systems use it as a foundational worked example. Hobbyists building audio equipment or small power supplies use the same relationship to pick or wind transformers for a target voltage. Enter the primary voltage and the winding turns to get the secondary voltage and ratio.