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Physics

Transformer Turns Ratio

Ns/Np = Vs/Vp. Free online Transformer Turns Ratio. Calculate transformer turns ratio online — fast, accurate, mobile-friendly, no signup needed.

V₁/V₂ = N₁/N₂.
Secondary turns
5

Derivation

  1. ├── 01GivenNp = 100, Vp = 240, Vs = 12
  2. ├── 02Formulat × e.Vs / a
  3. ├── 03Substitutet × e.12 / a
  4. └── 04Compute Secondary turns5
Did you know?

Ratios appear in the earliest Greek mathematics (Eudoxus, 4th century BCE) as a way to compare incommensurable lengths without a concept of irrational numbers.

§01What is

Understanding the Transformer Turns Ratio

The Transformer Turns Ratio computes Secondary turns from 3 inputs: primary turns, primary v, secondary v. Ns/Np = Vs/Vp.

Physics is the toolkit for turning a real-world observation into a prediction. Whether it’s a falling object, a moving car, or a stressed beam, the equations here are the same ones every engineer relies on. The Transformer Turns Ratio sits in that toolkit — it ns/Np = Vs/Vp. Enter your numbers above and the result updates instantly; every step of the math is shown in the Derivation panel so you can see exactly how the answer was reached.

§02The Formula

How it’s calculated

t × e.Vs / a

Where

Np
Primary turns
Vp
Primary V
Vs
Secondary V
§03Practical Example

Step-by-step walkthrough

Scenario

Apply the formula to a realistic set of inputs: Primary turns = 100, Primary V = 240, Secondary V = 12.

  1. 01Start by noting the input — Primary turns: 100.
  2. 02Start by noting the input — Primary V: 240.
  3. 03Start by noting the input — Secondary V: 12.
  4. 04Substitute these values into the formula: t × e.Vs / a
  5. 05Compute Secondary turns: the calculator returns 5.
  6. 06Cross-check the answer by opening the Derivation panel above — every line of math is shown so you can follow the computation end-to-end.
§04Variants

Common Transformer Turns Ratio Problems

The formula gets rearranged depending on which variable you need. Here are the patterns you’ll run into in the real world — find the one that matches your problem and follow the worked steps.

01 · PATTERN

Primary turns halved

Np = 50 (from 100)

Keep every other input at its default and halve the primary turns. See how secondary turns responds.

  1. 01New Primary turns: 50
  2. 02Baseline Secondary turns: 5
  3. 03New Secondary turns: 2.5
  4. 04Secondary turns decreases by 50% → use this sensitivity to plan for real-world variation.
02 · PATTERN

Primary turns doubled

Np = 200 (from 100)

Keep every other input at its default and double the primary turns. See how secondary turns responds.

  1. 01New Primary turns: 200
  2. 02Baseline Secondary turns: 5
  3. 03New Secondary turns: 10
  4. 04Secondary turns increases by 100% → use this sensitivity to plan for real-world variation.
03 · PATTERN

Primary V halved

Vp = 120 (from 240)

Keep every other input at its default and halve the primary v. See how secondary turns responds.

  1. 01New Primary V: 120
  2. 02Baseline Secondary turns: 5
  3. 03New Secondary turns: 10
  4. 04Secondary turns increases by 100% → use this sensitivity to plan for real-world variation.
04 · PATTERN

Primary V doubled

Vp = 480 (from 240)

Keep every other input at its default and double the primary v. See how secondary turns responds.

  1. 01New Primary V: 480
  2. 02Baseline Secondary turns: 5
  3. 03New Secondary turns: 2.5
  4. 04Secondary turns decreases by 50% → use this sensitivity to plan for real-world variation.
§05FAQ

Frequently asked questions

Yes. The calculator implements the standard formula as documented and returns exact floating-point results. No approximations are used unless noted in the formula.
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