Transformer Calculator
Calculate transformer step by step: Vs ÷ Vp = Ns ÷ Np, and for an ideal transformer Ip ÷ Is = Ns ÷ Np.
In short
Formula: Vs ÷ Vp = Ns ÷ Np, and for an ideal transformer Ip ÷ Is = Ns ÷ Np.
Secondary voltage
11.96 V
- Turns ratio (Np:Ns)
- 19.2308 : 1
What this calculator does
Calculate transformer step by step: Vs ÷ Vp = Ns ÷ Np, and for an ideal transformer Ip ÷ Is = Ns ÷ Np. Worked example, questions and limitations included.
Use it to turn Primary voltage, Primary turns, Secondary turns, Secondary load current (optional) into a checked result you can compare, copy, or rerun with different assumptions.
The page shows the formula, a numeric worked example, and the assumptions that affect this electrical calculation.
Inputs and what they mean
- Primary voltage
- — number value.
- Primary turns
- — number value.
- Secondary turns
- — number value.
- Secondary load current (optional)
- — number value.
How to use it
- Enter each value in the unit shown next to the box (use the unit converter first if your numbers are in other units).
- Check the breakdown to see every intermediate step.
- Read the limitations before relying on the result.
Formula
Ideal transformer: no copper, core or leakage losses.
Turns must be above zero.
Power in equals power out in the ideal case.
Vs ÷ Vp = Ns ÷ Np, and for an ideal transformer Ip ÷ Is = Ns ÷ Np.
Inputs used: Primary voltage, Primary turns, Secondary turns, Secondary load current (optional).
Worked example
230 V, 1000:52 turns
- Ratio = 1000 ÷ 52 = 19.23.
- Vs = 230 ÷ 19.23 = 11.96 V.
Reading the result
The headline figure is the main answer. Any breakdown underneath shows the parts that make it up, so you can check the working and see what changes when you adjust an input.
Limitations and assumptions
- Ideal, lossless model.
- Does not check core saturation or VA rating.
- Single-phase ratio only.
- Results are estimates for planning and learning. Real designs, installations and bids must be checked by a qualified, licensed professional against the codes that apply where you work.
- The result depends on the values you enter for this transformer calculator; it does not supply missing rates, rules, prices, dates, or assumptions for you.
Common questions
Why is the real output voltage different?
Real transformers have winding resistance and leakage, so voltage sags under load. Nameplate ratings are usually quoted at full load.
Does a transformer work on DC?
No. It needs a changing current to induce voltage in the secondary.
How is current affected?
Current changes in the opposite direction to voltage: stepping voltage down steps current up by the same ratio. Check the formula, example, and limitations on this page before using the result for a real electrical decision.
How do I use the Transformer Calculator?
Enter the required values for Primary voltage, Primary turns, Secondary turns, Secondary load current (optional). The calculator applies the formula on this page and shows the main result with any supporting breakdown so you can check the arithmetic.
What formula does the Transformer Calculator use?
Vs ÷ Vp = Ns ÷ Np, and for an ideal transformer Ip ÷ Is = Ns ÷ Np. The visible formula section above lists the calculation path and the edge cases the page handles, so the result can be checked without relying on the form alone.
Can the Transformer Calculator be used for exact decisions?
Use it as a calculation aid, not as a substitute for checking the underlying rule, contract, policy, or professional advice that applies to your situation. When a result depends on local rules, personal details, prices, or dates, enter those values yourself and confirm them before acting.
Related tools
Calculate electrical power step by step: P = V × I = I² × R = V² ÷ R (DC or resistive AC using RMS values).
Calculate voltage divider step by step: Vout = Vin × R2 ÷ (R1 + R2).
Calculate resistance step by step: R = V ÷ I, or for a conductor R = ρ × L ÷ A (A in m²).