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How to calculate the suction force of a strong neodymium(NdFeB) magnet?

Apr 16,2021 / News, Industry News / Author: ShengKui

The magnetic force of a neodymium iron boron magnet is 640 times its own weight, which means it can absorb 640 times its own weight. Under normal circumstances, neodymium iron boron magnets can absorb objects 600 times their own weight. Because there are many specifications and shapes of neodymium iron boron magnets, there are magnets with holes and special-shaped magnets, which have a direct relationship with the attractive force.

Here we only list two simple specifications: round and square.

Example: square neodymium iron boron magnet, the brand is: N35 specification: 30mm×15mm×5mm, the calculation formula of magnet attraction: magnet volume×density×600 (multiples)

1. Magnet density: The approximate density of N35 is about 7.5 g/cm3

2. Magnet weight: volume×density (30mm×15mm×5mm)×0.0075=16.875g

3. Magnet attraction: 16.875×600=10125 grams

It can be seen that a 30mm×15mm×5mm square magnet can pick up about 10.1kg of objects.

Another example: round N35 neodymium iron boron magnet with 20mm*5mm strength

Suction = (10 radius * 10 radius * 3.14 * 5 thickness) volume * 0.0075 density * 600 times = 7065g (g) In other words, 20 * 5 N35 magnet can absorb 7.065 kg of objects.

If your magnet specifications are of these two specifications, you can directly apply the formula to calculate. Please note that the size unit is mm (millimeters), not this unit needs to be converted. For more calculation, you can contact us at

Attached permanent magnet magnetic force calculation formula F=BILsinθ

F is the magnetic field force, also called ampere force, B is the magnetic induction intensity, I is the current in the wire, L is the length of the wire, and θ is the angle between B and the wire. The magnetic pole formula: F=mH, where m is the magnetic pole strength, H is the magnetic field strength, and the magnetic field strength generated by the magnetic poles is inversely proportional to the third power of the distance r.