I saw many friends on the Internet looking for the formula for calculating the weight of magnets. Today, Xiaofu, the manufacturer of courage magnets, will share with you the weight calculation method of round, ring and block magnets for neodymium magnets.
Magnets of different materials have different densities and need to be replaced before calculation. The following calculation formulas are all taking neodymium magnets as an example, and the density of ferrite is 4.9.

For example: NdFeB Magnet F20x10x3mm, where the density is calculated as 7.5
The formula is: 20*10*3*7.5/1000=4.5g,
The formula for calculating the weight of disc Nd-Fe-B magnet is as follows: (density is calculated by 7.5)
For example, the disc magnet specification is 20.5 x 8.9mm
The formula is: area x thickness x density/1000 = weight (g), that is
7.5 x 3.14 x 20.5² x 8.9/4000=22.02g或7.5 x 3.14 x 10..25² x 8.9/1000=22.02g
Formula for calculating the weight of ring magnet
π x (a+b)(a-b) x c(thickness) x p(density)/4000 [where A and B represent length and width respectively]
For example, the weight of a magnet with an outer diameter of 12mm, an inner diameter of 7mm and a thickness of 3mm is; 3.14 x (12+7) x (12-7) x3 x 7.5/4000 is approximately equal to 1.7g
As for the calculation formula of the motor arc magnet, Xiaofu can't do it yet.
This article is originally shared by Xiaofu, a china magnet manufacturer, to learn more about magnets by clicking on the magnet question and answer.
Related magnet calculation tools;
Magnetic pull force online calculation
This is a very small rectangular ferrite block magnet, measuring 2.45 mm in length and 1 mm in both width and height. It is magnetised along its length and is barely noticeable when held in the hand....
7.4x6x5mm Ferrite Small Block Magnet Introduction,Material: Hard Ferrite (Ceramic),Shape: Block / Rectangle / Bar,Coating: No Coating,Grade (Chinese Stardard): Y30,Operating temperature: -40°C to 250°C,Delivery time: 7-15 days,Magnetization direction: thickness....
U-shaped neodymium magnets are a type of high-performance permanent magnet material with a structure resembling the letter ‘U’. Manufactured from sintered neodymium-iron-boron, they are characterised by high magnetic energy product....
This is a radial 4-pole ring (Hollow cylinder) magnet, the material is bonded NdFeB, with high magnetic performance, the size is 16mm outer diameter, inner hole 5mm, height 20mm, surface gray epoxy treatment, suitable for water pump motor...
This product is a 4-pole ring magnet, injection-molded ferrite material, the sample size is 22mm outer diameter, 7mm inner diameter, 4mm thickness, 2 N poles and 2 S poles, mainly used for push rod motors, magnetic induction devices, encoders, etc.,...
This is a radial 2 pole circular magnet designed specifically for magnetic encoder chips. It is made of sintered neodymium-iron-boron with N35 grade performance and is suitable for standard environments....
This product is a multi pole magnetic ring with an inner diameter of 1.5mm. The material is injection molded ferrite. It adopts axial multi pole magnetization and is mainly used for DC motors. If you have a sample of similar injection molded magnetic products, please contact us for quotation....
This is a very small size rectangular block magnet with galvanized surface, 3mm length, 1.5mm width and height, with very fine tolerance, magnetized by lengthwise direction, mainly used in precision electronics, instrumentation, please contact us if you need to buy....