Transformer Turns and Voltage Calculator
Calculate the ideal AC voltage ratio and a simplified efficiency-based current and power balance. Keep ideal voltage scaling separate from entered losses.
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Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Scale voltage by secondary-to-primary turns. With the stated unity-power-factor assumption, input power is primary RMS voltage times current. Apply the entered efficiency and divide output power by ideal secondary voltage.
Vs/Vp=Ns/Np; Pin=VpIp; Pout=ηPin; Is=Pout/Vs
Worked example
A 1000:100 turns transformer with 230 V RMS, 1 A primary current and 95% efficiency gives ideal secondary voltage 23 V, output power 218.5 W and secondary current 9.5 A.
Assumptions and input details
AC only. Turns are integers 1–1e6; primary voltage is positive and current nonnegative. Efficiency is greater than zero and at most 100%. This model assumes unity power factor on both sides and an ideal voltage ratio even when power losses are entered. Efficiency changes the power/current balance, not the ideal voltage ratio. Magnetizing/no-load current, saturation, winding impedance, regulation, frequency/core sizing and load phase are omitted. It is a model calculation, not a transformer design or rating.
References: OpenStax transformers
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
SI prefixes are explicit: for example, milli means one thousandth, micro one millionth and kilo one thousand. Changing a unit changes the interpretation of the entered number.
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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