Physics

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Ideal Transformer Calculator.

Calculate secondary voltage from turns ratio and primary voltage.

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01

Set your values

Results update as you type.

Secondary voltage: 12

Secondary voltage

0.000000
Turns ratio: 0.1

Turns ratio

0.000000

Educational SI models with assumptions stated in each description; verify engineering decisions independently.

Use Cases

Design a step-down transformer

Determine the secondary voltage when you know the primary voltage and the number of turns on both windings, helping you design a transformer for a specific output voltage.

Example: Primary 120 V, 1000 turns primary, 100 turns secondary gives 12 V.

Verify transformer specifications

Check if a transformer's turns ratio matches its rated output voltage, useful for troubleshooting or selecting a replacement.

Example: Check a 240 V to 24 V transformer with 2000 primary turns and 200 secondary turns.

Frequently Asked Questions

How do I calculate the secondary voltage of an ideal transformer?
Enter the primary voltage, primary turns, and secondary turns. The calculator uses the ideal transformer equation: V_secondary = V_primary × (N_secondary / N_primary).
What is the turns ratio in a transformer?
The turns ratio is the number of turns in the secondary winding divided by the number of turns in the primary winding. It determines how the voltage is stepped up or down.
Does this calculator account for losses or efficiency?
No, it assumes an ideal transformer with 100% efficiency and no losses. Real transformers have small losses, but this calculator provides the theoretical secondary voltage.

Tips & Common Mistakes

Tips

  • Ensure the primary and secondary turns are positive integers; the calculator expects whole numbers.
  • If the secondary turns are greater than primary turns, the transformer steps up voltage; if less, it steps down.
  • Use consistent units: voltage in volts and turns as counts. The calculator handles the ratio automatically.
  • For real transformers, consider efficiency and losses; this ideal calculator gives the theoretical maximum.

Common Mistakes to Avoid

  • Entering the turns ratio directly instead of the actual number of turns for primary and secondary.
  • Confusing primary and secondary turns, which would invert the voltage transformation.
  • Assuming the calculator accounts for real-world losses or load effects; it only computes ideal voltage.

Last updated: August 13, 2026