Transformer Turns Ratio Calculator
Enter primary turns and either secondary turns or primary voltage to estimate the ideal ratio and output voltage.
A QUICK WALKTHROUGH
How to use this tool
- Enter primary turns, secondary turns, and primary voltage.
- Calculate the turns ratio and ideal secondary voltage.
- Compare the ideal result with real transformer ratings.
Ideal relationship
Turns ratio Np:Ns = Vp:Vs. The voltage estimate assumes an ideal transformer with no losses, regulation drop, or load effect.
Input boundary
Enter finite positive winding turns and primary voltage. Turns may be decimal for an effective ratio, although physical windings are normally whole turns.
Local calculation
Values are calculated in your browser and are not uploaded or stored.
GOOD TO KNOW
Common questions
What does a 10:1 ratio mean?
The primary has ten times as many turns as the secondary, so the ideal secondary voltage is one tenth of the primary voltage.
Does this predict loaded voltage?
No. It estimates the ideal no-load voltage; winding resistance, losses, regulation, frequency, and load are not modeled.
Can turns be fractional?
The calculator accepts positive decimals for an effective ratio, but a real winding design must use physically realizable turns.