Permeability describes how easily a material supports a magnetic field. Iron cores multiply the field of a coil thousands of times; copper and water are very slightly diamagnetic and weaken it.
How to use the Magnetic Permeability Calculator
- Input
- Material
- Relative permeability μ_r
- Permeability μ (H/m)
- Susceptibility χ
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Choose a material or enter one of the three quantities.
Inputs explained
| Field | What to enter |
|---|---|
| Input | Choose one: Material preset, Relative permeability μ_r, Permeability μ, Susceptibility χ |
| Material | Choose one: Vacuum, Air, Water, Copper … |
| Relative permeability μ_r | A number |
| Permeability μ (H/m) | A number |
| Susceptibility χ | A number |
What each result means
- Permeability μ = [Relative permeability μ_r]×1.25663706212e-06
- Susceptibility χ = [Relative permeability μ_r] – 1
Example values
How the main result changes when Relative permeability μ_r changes and everything else stays at the example values above:
| Relative permeability μ_r | Relative permeability μ_r |
|---|---|
| 500 | 5,000 |
| 750 | 5,000 |
| 1,000 | 5,000 |
| 1,250 | 5,000 |
| 1,500 | 5,000 |
| 2,000 | 5,000 |
Formula
μ = μ_r·μ₀, χ = μ_r − 1, μ₀ = 1.25664 × 10⁻⁶ H/m
Worked example
Inputs — Input: Material preset; Material: Iron (99.8%).
Results — Relative permeability μ_r = 5,000; Permeability μ = 0.006283 H/m; Susceptibility χ = 4,999; Magnetic behaviour = Ferromagnetic / ferrimagnetic.
Key terms
- Susceptibility
- Magnetisation per unit applied field.
Frequently asked questions
What is μ₀?
The vacuum permeability, about 1.2566 × 10⁻⁶ H/m.
What is diamagnetism?
Weak repulsion from magnetic fields (χ < 0).
Is μ_r constant for iron?
No – it depends on field strength and saturates.
Why use mu-metal?
Its very high permeability makes excellent magnetic shields.