What is the Transformer Turns Calculator?

This tool applies the core principles of an ideal transformer to determine an unknown value (voltage, number of turns, or current) when three related values are known. The relationship, known as the turns ratio, is fundamental to understanding how transformers step up or step down AC voltage and current.

Why the Turns Ratio is Important

The turns ratio ($\frac{N_p}{N_s}$) defines the entire behavior of the transformer. In an ideal transformer, the ratio of voltages is directly proportional to the ratio of turns, but inversely proportional to the ratio of currents. This principle allows engineers to:

• Voltage Step-Up/Step-Down: Increase (step-up) or decrease (step-down) the AC voltage for efficient power transmission or safe local use.
• Current Transformation: Decrease (step-down) current when voltage is stepped up, maintaining the conservation of power ($P=IV$).
• Impedance Matching: Optimize power transfer between circuits with different impedances (e.g., connecting an audio amplifier to a speaker).

How to Use the Calculator

1. Identify the Unknown: Determine which of the six variables ($V_p, V_s, N_p, N_s, I_p, I_s$) you need to find.
2. Enter Known Values: Input numerical values into exactly three of the remaining input fields that are related to the unknown (i.e., they must form a proportion like $\frac{A}{B}=\frac{C}{D}$). Leave the field for the unknown value empty.
3. Check for Validity: The calculator works if your three known values and one unknown value form one of the following proportional sets:
   • $\{V_p, V_s, N_p, N_s\}$ (Voltage and Turns)
   • $\{V_p, V_s, I_p, I_s\}$ (Voltage and Current)
   • $\{N_p, N_s, I_p, I_s\}$ (Turns and Current)
4. Calculate: Click the “Calculate Missing Value” button.
5. Review Results: The “Calculation Results” section will appear, showing the formula used, the step-by-step substitution (rendered with MathJax), and the final calculated value, rounded to two decimal places.