Calculating your turns ratio (primary : secondary) is straightforward once you know the Transformer Turns Ratio formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the Transformer Turns Ratio Calculator.
What is Transformer Turns Ratio?
The Transformer Turns Ratio calculation tells you your turns ratio (primary : secondary) from a few simple inputs. The figure you are solving for here is the turns ratio (primary : secondary).
The Transformer Turns Ratio formula
The core formula is:
Turns ratio (primary : secondary) = Primary voltage ÷ Secondary voltageHere is what each input means:
- Primary voltage — a value measured in V. Example: 230 V.
- Secondary voltage — a value measured in V. Example: 12 V.
- Primary turns — a number. Example: 1,000.
How to calculate it step by step
- Write down the primary voltage (for example, 230 V).
- Write down the secondary voltage (for example, 12 V).
- Write down the primary turns (for example, 1,000).
- Apply the formula above to get your turns ratio (primary : secondary).
- Double-check the result with the Transformer Turns Ratio Calculator.
Worked examples
Example 1
| Input / Output | Value |
|---|---|
| Primary voltage | 230 V |
| Secondary voltage | 12 V |
| Primary turns | 1,000 |
| Turns ratio (primary : secondary) | 19.167 |
| Secondary turns | 52 |
With primary voltage of 230 V, secondary voltage of 12 V and primary turns of 1,000, the turns ratio (primary : secondary) works out to 19.167.
Example 2
With primary voltage of 460 V, secondary voltage of 12 V and primary turns of 1,000, the turns ratio (primary : secondary) works out to 38.333.
| Result | Value |
|---|---|
| Turns ratio (primary : secondary) | 38.333 |
| Secondary turns | 26 |
Example 3
With primary voltage of 120 V, secondary voltage of 12 V and primary turns of 1,000, the turns ratio (primary : secondary) works out to 10.000.
| Result | Value |
|---|---|
| Turns ratio (primary : secondary) | 10.000 |
| Secondary turns | 100 |
Tips for an accurate result
- Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
- Round only at the very end. Rounding inputs early can shift the final answer noticeably.
- Re-run the numbers whenever an input changes, rather than estimating from an old result.
Prefer not to do the maths by hand? — the Transformer Turns Ratio Calculator does it instantly, for free, with the formula and a worked example built in.
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