---
title: Calculating Magnetic Permeance Coefficients | Bunting
description: Magnetic Permeance Coefficients
---

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# [Calculating Magnetic Permeance Coefficients | Bunting](https://www.magnetapplications.com/blog/calculating-magnetic-permeance-coefficients)

 Written by [Bunting DuBois](https://www.magnetapplications.com/blog/author/bunting-dubois) | 30 Apr 2024

Magnetic permeance coefficient, often denoted as **Pc**, is a measure used in the design of magnetic circuits. It is defined as the ratio of magnetic flux density **Bd** to magnetic field strength **Hd** at the operating point on the B-H curve of a magnet. This coefficient helps to express the “operating point,” or “operating slope,” of the magnet on the B-H curve, which is crucial for understanding how the magnet will perform under different conditions. It should be noted that the permeance coefficient of a single body magnet is largely affected by the magnet’s shape. Considering a cylindrical shape, magnets with smaller L/D ratios have lower **Pc** when the direction of magnetization is along the part’s length.

Here’s a brief explanation of the concept:

- **Magnetic Flux Density Bd**: This represents the amount of magnetic flux passing through a unit area perpendicular to the direction of the magnetic field.
- **Magnetic Field Strength Hd**: This is a measure of the magnetizing force required to create a certain magnetic field in a material.
- **B-H Curve**: This curve shows the relationship between magnetic flux density and magnetic field strength for a given material.

The permeance coefficient is particularly useful in predicting the performance and demagnetization resistance of a magnet in a magnetic circuit, and is essential for engineers when designing and analyzing magnetic systems.

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