Transformer Turns Ratio Calculator
Secondary voltage and current from a transformer's turns ratio.
Enter your values
Enter the primary turns you are working with.
Enter the secondary turns you are working with.
Enter the primary voltage in V.
Enter the primary current in A.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Turns ratio
- 10:1
- Secondary voltage
- 24 V
- Secondary current
- 10 A
Quick answer
Vs/Vp = Ns/Np, and Is/Ip = Np/Ns.
Vs = Vp x (Ns/Np)
At a glance
| What it does | Secondary voltage and current from a transformer's turns ratio. |
|---|---|
| Category | Engineering |
| Inputs needed | Primary turns, Secondary turns, Primary voltage, Primary current |
| Main output | Turns ratio |
| Formula | Vs = Vp x (Ns/Np) |
| Cost | Free — no sign-up, no download |
How to use the Transformer Turns Ratio Calculator
- 1Enter the number of turns on the primary and secondary windings.
- 2Enter the primary voltage and current.
- 3Read the resulting secondary voltage and current (ideal transformer, no losses).
Inputs explained
- Primary turns
- Enter the primary turns you are working with.
- Secondary turns
- Enter the secondary turns you are working with.
- Primary voltage(V)
- Enter the primary voltage in V.
- Primary current(A)
- Enter the primary current in A.
Worked example
Using the values the calculator loads with:
Inputs
- Primary turns1000
- Secondary turns100
- Primary voltage240 V
- Primary current1 A
Results
- Turns ratio10:1
- Secondary voltage24 V
- Secondary current10 A
Frequently asked questions
Step-up or step-down?
If secondary turns exceed primary turns it steps voltage up and current down, and vice versa.
Does power stay the same?
In an ideal transformer, input power equals output power; real transformers lose a small amount to heat.
What do I need to enter into the Transformer Turns Ratio Calculator?
Just 4 values: primary turns, secondary turns, primary voltage, primary current. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Transformer Turns Ratio Calculator work out the answer?
Vs/Vp = Ns/Np, and Is/Ip = Np/Ns. It applies the formula Vs = Vp x (Ns/Np) and shows the working so you can check each step by hand.
Is the Transformer Turns Ratio Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.