The Transformer Turns Ratio Calculator works out your turns ratio (primary : secondary), along with 1 related figure in an instant. Enter primary voltage, secondary voltage and primary turns and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.
Enter the primary voltage.
Enter the secondary voltage.
Enter the primary turns.
Read off your turns ratio (primary : secondary), together with secondary turns — the calculator updates automatically, with no button to press.
Formula
The Transformer Turns Ratio Calculator uses the formula:
Turns ratio (primary : secondary) = Primary voltage ÷ Secondary voltage
Worked example
For example, with primary voltage of 230 V, secondary voltage of 12 V and primary turns of 1,000, the turns ratio (primary : secondary) is 19.167.
Inputs used
Primary voltage
230 V
Secondary voltage
12 V
Primary turns
1,000
Results
Turns ratio (primary : secondary)
19.167
Secondary turns
52
Results are estimates for educational use, not professional advice.
Key terms explained
Ratio
A comparison of two quantities showing how many times one contains the other.
Frequently asked questions
It is the ratio of primary to secondary voltage, which equals the ratio of primary to secondary turns. 230 V to 12 V is about 19:1.
Multiply primary turns by the secondary voltage and divide by the primary voltage.
One with more primary than secondary turns, so it lowers the voltage. A step-up transformer does the reverse.
Yes. As voltage steps down, current steps up by roughly the same ratio, since power is conserved.
The Transformer Turns Ratio Calculator uses the formula: Turns ratio (primary : secondary) = Primary voltage ÷ Secondary voltage. For example, with primary voltage of 230 V, secondary voltage of 12 V and primary turns of 1,000, the turns ratio (primary : secondary) is 19.167.
Enter the primary voltage. Enter the secondary voltage. Enter the primary turns. Read off your turns ratio (primary : secondary), together with secondary turns — the calculator updates automatically, with no button to press.
Reference table of turns ratio (primary : secondary) for Transformer Turns Ratio across a range of primary voltage values — exact, engine-computed figures you can read off at a glance.