Advanced physics calculator for magnetic pull force analysis. Calculate precise magnetic flux density easily. Evaluate magnet performance instantly.
Calculating the pull force of a Neodymium (NdFeB) magnet requires determining the magnetic flux density ($B_z$) along its central axis at a distance $z$, and then applying the Maxwell Stress Tensor equation. For a cylindrical disc magnet, the on-axis magnetic flux density $B_z$ is derived using the Biot-Savart Law:
$$B_z(z) = \frac{B_r}{2} \left[ \frac{z + L}{\sqrt{(z + L)^2 + R^2}} - \frac{z}{\sqrt{z^2 + R^2}} \right]$$
Where $B_r$ represents the material remanence, $L$ is the thickness along the direction of magnetization, $R$ is the radius, and $z$ is the distance from the magnet face. For rectangular blocks, the formula uses trigonometric arc-tangent relations across face dimensions. Once $B_z$ is known, the pull force against a thick mild steel surface is evaluated using the method of images:
$$F = \frac{(2 \cdot B_z)^2 \cdot A}{2 \mu_0}$$
Where $A$ is the pole surface area, and $\mu_0 = 4\pi \times 10^{-7} \text{ T}\cdot\text{m/A}$ is the permeability of free space.
Using this tool is straightforward. First, select your Neodymium magnet grade (e.g., N35, N42, N52) and choose the appropriate geometric shape. Next, enter the dimensions in millimeters. Ensure that the thickness corresponds to the distance between the two magnetic poles. Enter any air gap distance representing non-magnetic coatings, paint layers, or physical spacing. Finally, press "Calculate Force" to display results above the form.
Neodymium magnets represent the strongest class of permanent rare-earth magnets available commercially. Their exceptional performance is due to their high remanence ($B_r$) and coercivity. When evaluating holding power, several physical variables dictate the real-world pull force. Understanding these variables ensures optimal engineering decisions when designing assemblies, latches, or magnetic separators.
The air gap is the single most critical factor reducing magnetic attraction. Because magnetic field intensity decays exponentially over distance, even a fractional millimeter gap dramatically drops total force. Surface treatments such as epoxy plating, rubber jackets, or heavy powder coatings act as artificial air gaps. Designers must account for these layers when evaluating practical holding capacities in industrial environments.
Calculations assume contact with a flat, clean, and sufficiently thick mild steel target. If the steel target is too thin, it reaches magnetic saturation, preventing full flux absorption. As a result, thin sheet metals display significantly lower pull forces than theoretical predictions. Always ensure substrate thickness matches the magnet's scale to achieve maximum pull strength.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.