Custom neodymium magnets have various shapes, including rods, discs, blocks, and many other irregular shapes. However, we have different ways to tell the sizes of different shapes. They can be confusing if you don’t have much experience with magnets.
Osenc is a custom neodymium magnet supplier, and we’ve prepared a list to explain how to understand the sizes of custom neodymium magnets. They can be helpful for your communication with the suppliers.

1. Round & Cylindrical Neodymium Magnets

The way for round and cylindrical neodymium magnets is: D10 x 2 mm
If a round or cylindrical magnet has a dimension of D10 x 2 mm, that means its diameter is 10 mm, and the thickness is 2 mm. 

Note:

• Nowadays, most people use D instead of Φ, because D is easy to type using computers and mobile phones

2. Ring / Circular Neodymium Magnets

The way for ring / circular neodymium magnets is similar.

• D (or OD) for the outer diameter
• d (or ID)  for the inner diameter
• H for the thickness (height)

If a ring / circular neodymium magnet has a dimension of D10 x d7 x 3 mm, that means:

• Its outer diameter is 10 mm, the inner diameter is 5 mm, and the thickness is 2 mm.

Meanwhile, ring neodymium magnets have 2 types of holes: straight and countersunk holes.

• Straight holes are drilled vertically into the magnets
• Countersunk holes (also called screw holes) include a primary hole and a major hole.

For ring or circular neodymium magnets with a countersunk hole:

• D for the outer diameter
• M for the diameter of the major hole

If a ring magnet has a dimension of D10 x M7 x 2 mm, that means:

• Its outer diameter is 10 mm, the major hole diameter is 5 mm, and the thickness is 2 mm.
• Besides indicating the sizes, it’s always good to include the countersunk angle.

3. Block Neodymium Magnets

The dimension for block neodymium magnets:

• Length x Width x Height
• Usually, the dimension begins with an uppercase letter F

If a block neodymium magnet has a dimension of F8 × 4 × 2 mm, that means:

• Its length is 8 mm, the width is 4 mm, and the height is 2 mm.

Block magnets: Length x Width x Height (For example, 10 x 10 x 10 mm)

Block magnets with a hole: Length x Width x Height x Hole diameter (For example, 10 x 10 x 10 x D5 mm)

Block magnet with a countersunk hole: Length x Width x Height x Major hole diameter (For example, 10 x 10 x 10 x M5 mm)

By default, the last number is the magnetization direction of this magnet.

• Therefore, the magnetization direction is the direction of 2 mm, which is the thickness direction for magnetization.
• Meanwhile, N and S are the two bigger surfaces, namely the 8 × 4mm surface.
  One side is the N pole, and the other side is the S pole.

4. Arc Neodymium Magnets

The dimension for arc neodymium magnets will need to include:

• Outer radius (R1)
• Inner radius (R2)
• Radian
• Width

The magnetic surfaces are the inside and outside of the arc by default.

Note:

• The shapes of arc neodymium magnets require more numbers to define clearly.
• The dimension formula mentioned above is simplified for easy understanding.
• It’d be better to use technical sketches to indicate all the size information.

5. Spherical Neodymium Magnets

Comparatively, the dimension for spherical neodymium magnets is the simplest:

• D for the diameter

For example, if a spherical magnet has a dimension of D5 mm, that means its diameter is 5 mm.

The content above has explained how we usually tell the sizes of neodymium magnets of regular shapes. Osenc is a custom neodymium magnet supplier, and we also offer these strong magnets of irregular shapes.

Send us a sketch or a sample of the magnets you need, and we will give you the most favorable quote!