Enter the test frequency, magnetic permeability, and electrical conductivity into the calculator to determine the penetration depth.

Penetration Depth Formula

The following formula is used to calculate a Penetration Depth

d = 1 / SQRT ( pi*f*u*e)

  • Where d is the Penetration Depth (mm)
  • f is the test frequency (hz)
  • u is the magnetic permeability (H/mm)
  • e is the electrical conductivity (% IACS)

To calculate the Penetration Depth, take the reciprocal of the square root of the frequency multiplied by the magnetic permeability multiplied by the conductivity, multiplied by pi.

What is Penetration Depth?


A Penetration Depth is defined as the maximum distance a radiation will penetrate into a magnetic field.

How to calculate Penetration Depth?

Example Problem:

The following example outlines the steps and information needed to calculate a Penetration Depth.

First, determine the test frequency. In this example, the test frequency is found to be 50 hz.

Next, determine the magnetic permeability. For this problem, this is calculated to be 20 H/mm.

Next, determine the electrical conductivity. This is found to be 5%IACS.

Finally, calculate the Penetration Depth using the formula above;

d = 1 / SQRT ( pi*f*u*e)

d = 1 / SQRT ( 3.14159*50*20*5)

d = .00797 mm