The primary function of a power transformer is to step up or step down voltage as per the requirement. The magnitude of voltage transformation in a transformer depends on its turns ratio. The output voltage of any transformer can be theoretically calculated from its turns ratio. Use the following transformer ratio calculator for transformer ratio calculation.

## Transformer ratio calculator

**Calculate using**

**What is turns ratio?**

Each coil of a transformer contains a certain number of turns of the conductor. **Turns ratio** is defined as the ratio of the number of turns of the conductor in the primary coil to the number of turns of the conductor in the secondary winding. Let N_{p }be the number of turns of the conductor in the primary coil and N_{s} is the number of turns of the conductor in the secondary coil then turns ratio of the transformer can be given by the following equation:

**Turns ratio in an ideal transformer**

An ideal transformer is assumed to have zero winding impedance, zero leakage flux, and zero losses. For an ideal transformer, consider an ideal transformer with Np number of turns in the primary and Ns number of turns in the secondary. Let Vp be the voltage applied to the primary at a frequency of ‘f’, the Vp be the voltage measured at the secondary. Let φbe the flux linking both coils.

The voltage induced per turn of the primary is given by

**V**_{p }**/ N**_{p}** = k. φ**_{m}**.f**

Where k is a constant and φ_{m} is the maximum flux. From the above equation,

**φ**_{m}** = V**_{p }**/ N**_{p}**. k.f**

Since same flux links the primary and the secondary,

V_{s }/ N_{s} =
k. φ_{m}.f and φ_{m} = V_{s
}/ N_{s}. k.f

Hence, V_{p }/ N_{p}.
k.f = V_{s }/ N_{s}. k.f

**Therefore, V**_{p }**/ N**_{p}**= V**_{s }**/ N**_{s}** and V**_{p }**/ V**_{s}** = N**_{p}** / N**_{s}

**Relationship between Turns ratio and current**

For an ideal transformer, the input power is always equal to the output voltage.

Hence, V_{p}. I_{p}.
cosϕ = V_{s}. I_{s}. cosϕ

**Therefore, V**_{p }**/ V**_{s}**= I**_{s }**/ I**_{p}

Where I_{p} and I_{s }primary and
secondary current respectively.

Hence for an ideal transformer, the output current varies as the inversely proportional to the voltage. In a step-up transformer, the primary voltage can be stepped up based on the turns ratio but the load current capability of the same at the stepped-up voltage will reduce as the inverse of the turns ratio.