Ideal Transformer Calculator

Written by Great Medico

Updated September 25, 2026 •2 min read

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Electrical results can look precise while a unit, operating mode, or component assumption quietly changes the answer. Ideal Transformer Calculator keeps the calculation tied to the quantities on this page, so you can trace the transformer ratio and solved quantity back to the values you entered rather than treating it as a black-box number.

What this calculator does

The Ideal Transformer Calculator turns Primary windings, Secondary windings, Primary voltage, Secondary voltage, Primary current into the page’s transformer ratio and solved electrical quantity using the circuit or component relationship below. Where the page shows supporting quantities, they come from the same idealized model so you can cross-check the headline rather than reading one isolated number.

How to use it

Start with the fields that actually drive this result: Primary windings, Secondary windings, Primary voltage, Secondary voltage, Primary current. Keep units consistent with the menus beside the fields and avoid mixing values measured under different conditions. Enter one compatible primary/secondary ratio pair first—for example turns plus primary voltage—then add a current pair only if you want that side solved as well. After calculating, change one input at a time if you are comparing scenarios; that makes cause-and-effect much easier to see.

How the calculation works

An ideal transformer follows Np/Ns = Vp/Vs = Is/Ip. With any compatible primary/secondary pair entered, the page uses the turns ratio to solve the missing voltage, current, or winding quantity while assuming no loss.

Example

If Np = 100 turns, Ns = 20 turns, and Vp = 120 V, the ideal turns ratio gives Vs = 24 V. If primary current is 1 A at the same time, ideal power conservation gives secondary current of 5 A. Losses are intentionally absent from that example.

How to interpret the result

Interpret the solved turns, voltage, or current relationship as an ideal-transformer quantity for the exact mode and units entered. Use it to compare designs or check hand calculations, but keep component tolerances, ratings, frequency dependence, and real operating conditions in view before turning the number into a hardware decision.

Limitations and notes

This is an ideal transformer model: winding resistance, leakage inductance, magnetizing current, core loss, saturation, regulation, and efficiency are omitted. Blank default fields require you to enter a compatible pair before a meaningful result exists.