What is the formula for Transformer Turns-per-Volt?

The Transformer Turns-per-Volt formula is Turns/Volt = 1 / (4.44 × f × Bmax × A), where TPV—Turns per volt (turns/V); f—Frequency (Hz); Bmax—Working flux density (T); A—Core area (m²).

What does TPV mean in the Transformer Turns-per-Volt formula?

TPV is Turns per volt (turns/V).

Transformer Turns-per-Volt

Q: How do you calculate Transformer Turns-per-Volt?

Use the formula Turns/Volt = 1 / (4.44 × f × Bmax × A). Turns-per-volt is the practical design figure that tells a transformer winder how many turns to put on each winding per volt of desired output. Enter the values you know in the calculator above and it solves for the remaining variable.

TPV = 1 / (4.44 · f · Bmax · A)

Calculator

Turns per Volt

Frequency

Peak Flux Density

Core Area

Result

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Formula

Turns/Volt = 1 / (4.44 × f × Bmax × A)

Description

Turns-per-volt is the practical design figure that tells a transformer winder how many turns to put on each winding per volt of desired output. It is the reciprocal of the EMF equation per volt and depends only on the frequency, the chosen working flux density, and the core area. Multiply turns-per-volt by the winding voltage to get the number of turns.

Variables

TPV — Turns per volt (turns/V)
f — Frequency (Hz)
Bmax — Working flux density (T)
A — Core area (m²)

Practical Notes

A common shop rule for 50 Hz iron-core transformers is TPV ≈ 1/(4.44·f·B·A); designers add a few percent extra turns to the secondary to offset winding resistance and improve regulation.

Related Concepts

All Magnetics & Transformers formulas →

Transformer EMF Equation Transformer VA Rating Transformer Voltage Regulation Transformer Current Ratio Transformer Copper Loss Transformer Iron (Core) Loss Transformer Turns-per-Volt Transformer Impedance Matching

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