Transformer Calculator

Calculate voltage, current, and turn ratios for an ideal transformer.

Primary Side (Input)
Primary Voltage (V_p)
V
Primary Turns (N_p)
#
Secondary Side (Output)
Secondary Turns (N_s)
#
Load Current (I_s)
A
⚠️ Please enter valid numbers greater than 0.
Step-Down Transformer
12.0 V
Secondary Output Voltage (V_s)
0.5 A Primary
Current (I_p)
10 : 1 Turn Ratio
(N_p : N_s)
60.0 VA Total Apparent Power
10:1 Step-Down

How Ideal Transformers Work

Transformers operate on the principle of electromagnetic induction. They transfer electrical energy from one circuit to another through a magnetic core, without any direct electrical connection.

  • The Core Rule: The ratio of the number of turns in the primary coil ($N_p$) to the secondary coil ($N_s$) dictates exactly how the voltage will change.
  • The Equations: V_p / V_s = N_p / N_s = I_s / I_p
  • Conservation of Energy: A transformer does not create power ($P = V \times I$). Therefore, if the voltage is stepped up, the current must step down proportionally to maintain the same total power on both sides of the core.