Transformer Turns Ratio Calculator
Voltage ratio and secondary turns of a transformer from the primary and secondary voltages.
Results
Ratio
16.6667
Number
60.0
What this tool does
In an ideal transformer, voltages follow the turns ratio and currents follow its inverse, so a step-down transformer that divides the voltage by ten multiplies the available current by ten. Real transformers lose a few percent to winding resistance and core losses.
Formula
Up ÷ Us = Np ÷ Ns = Is ÷ Ip
Variables
| Symbol | Meaning | Unit |
|---|---|---|
up | Voltage | V |
us | Voltage | V |
np | Number | — |
k | Ratio | — |
ns | Number | — |
Worked example
- Voltage400 V
- Voltage24 V
- Number1000
- Ratio16.6667
- Number60.0
Limitations
- The formula assumes ideal conditions: no friction losses, no air resistance and no efficiency losses unless you enter them.
- Electrical installations are governed by national wiring rules. Cable sizing also depends on installation method, grouping, ambient temperature and protection devices, which this calculator does not evaluate.