Transformers and Power Supplies
Transformer Turns Ratio Calculator
Calculate secondary voltage from primary voltage and turns ratio Ns/Np. The default values illustrate the workflow; replace them with measurements or ratings from one documented condition.
Enter values for Secondary voltage
Enter ratings or measurements that describe one scenario.
Formula used on this page
This page evaluates Vs = Vp × Ns/Np. Only Primary voltage and Turns ratio Ns/Np enter the numerical result.
With the current entries, the primary answer is 23.92 V. Preserve the raw inputs when replacing this example.
Calculate secondary voltage from primary voltage and turns ratio Ns/Np. If you also need primary current, continue with Current Transformer Ratio Calculator.
Input notes
Use voltage and current values from the same side of the transformer or converter. A source note beside each entry makes the result reproducible.
Use the displayed unit for every field and document conversions separately. A connected part of the work can be checked with Current Transformer Reading Calculator.
- Primary voltage
- Default example: 230 V. Enter primary voltage in V.
- Turns ratio Ns/Np
- Default example: 0.104. Enter turns ratio Ns/Np.
Input quality checks
An unlabeled assumption can make an otherwise correct result unusable.
Verify sign, scale, and physical meaning before accepting the number.
Where this estimate can fail
Loaded secondary voltage also depends on regulation.
Additional checks may be needed for isolation, creepage, waveform shape, and manufacturer operating limits. Document which effects were checked elsewhere in the analysis.
Use voltage and current values from the same side of the transformer or converter.
A second scenario
Change Primary voltage from 230 V to 276 V without altering the remaining fields. The calculated value shifts from 23.92 V to 28.70 V.
The comparison demonstrates sensitivity, not a guaranteed field response.
Review the case step by step
Review primary voltage and the remaining entries as one case. If one value belongs to another temperature, load, or time period, separate the scenarios.
The displayed secondary voltage should be checked against a no-load, nominal-load, and limiting-load case. Investigate an unexpected magnitude before changing the model or adding margin.
Keep a baseline and vary the least certain measurement first. A separate analysis may be needed for isolation, creepage, waveform shape, and manufacturer operating limits.
Common questions before using the result
What else is required before final selection?
The calculator does not approve equipment or supply an unexplained margin. Compare against voltage stress, current stress, ripple, loss, regulation, and temperature.
Should intermediate values be rounded?
Do not round between dependent calculations. Match the final display to the precision of the source data.