Ideal Transformer Calculator

An ideal transformer changes voltage and current by its turns ratio while conserving power.

How the Math Works

The Ideal Transformer Calculator uses the fundamental transformer equation that relates primary and secondary voltages to their respective coil turns. The formula V_s/V_p = N_s/N_p expresses that the voltage ratio equals the turns ratio in an ideal transformer with no energy losses. If you know any two of the three values (primary voltage, secondary voltage, or turns ratio), you can solve for the unknown. For example, with a 1000:1 turns ratio and 120V primary, the secondary voltage calculates to 0.12V. This relationship holds regardless of whether you're stepping voltage up or down.

Practical Applications

To use this calculator practically, first determine your transformer's primary voltage and count the number of coil turns on both the primary (N_p) and secondary (N_s) windings. Enter these values into the calculator to instantly find the output voltage. This is essential when designing power supplies, matching audio equipment impedances, or determining if a transformer can step voltage to the levels needed for specific devices. Electricians and electronics technicians rely on this calculation when replacing or selecting transformers to ensure proper voltage conversion for safe device operation.

Day-to-Day Use

Understanding transformer calculations helps explain how the electrical power delivered to your home gets safely reduced from high-voltage transmission lines to the 120V or 240V outlets in your house. When you plug a device into a wall adapter that converts 120V AC to 12V DC for your router, transformer principles make that voltage reduction possible. Even when using a simple doorbell transformer that converts household 120V down to 8V for your doorbell, this calculation ensures your chime gets exactly the right voltage to work properly without burning out.

Worked example

230 V, 1000:100 turns → 23 V secondary at 10 A.

FAQ