Choose a disc magnet for a round pocket or a compact flat hold, a block magnet for a flat or long contact area, and a ring magnet when a screw, pin or shaft has to pass through the middle. For pure holding on flat steel, a disc beats a ring of the same size, because the hole removes magnet material: in our supplier data a 20 x 10 mm (0.79 x 0.39 in) disc pulls approx. 12 kg (26.5 lb), a 20 x 10 x 10 mm (0.79 x 0.39 x 0.39 in) ring approx. 6.6 kg (14.6 lb).
What is the difference between disc, block and ring magnets?
A disc (or cylinder) magnet is round and usually magnetised through its thickness, so the poles are on the flat faces. A block magnet is rectangular. A ring magnet is a disc with a hole in the center. Ring sizes are listed as outer diameter x inner diameter x height, block sizes as length x width x height. See all our magnets by shape.
Which magnet shape holds the most?
For the same outer size and grade, the shape with the most magnet material and the largest contact face holds most. The table compares sizes with the same outer dimensions (supplier pull forces, straight off a thick steel plate). Note the grades: the rings here are N50 and still hold less than the N48 discs.
| Product | Shape, size, grade | Pull force (kg) | Pull force (lb) |
|---|---|---|---|
| Neodymium Disc Magnet 20 x 10 mm, Nickel-Plated | Disc 20 x 10 mm (0.79 x 0.39 in), N48 | approx. 12 | 26.5 |
| Neodymium Ring Magnet 20 x 10 x 10 mm N50 | Ring 20 x 10 x 10 mm (0.79 x 0.39 x 0.39 in), N50 | approx. 6.6 | 14.6 |
| Neodymium Block Magnet 20 x 20 x 10 mm N48 | Block 20 x 20 x 10 mm (0.79 x 0.79 x 0.39 in), N48 | approx. 14 | 30.9 |
| Neodymium Disc Magnet 25 x 10 mm, Nickel-Plated | Disc 25 x 10 mm (0.98 x 0.39 in), N48 | approx. 15 | 33.1 |
| Neodymium Ring Magnet 25 x 10 x 10 mm | Ring 25 x 10 x 10 mm (0.98 x 0.39 x 0.39 in), N50 | approx. 8.4 | 18.5 |
| Neodymium Block Magnet 25 x 25 x 10 mm N48 | Block 25 x 25 x 10 mm (0.98 x 0.98 x 0.39 in), N48 | approx. 16 | 35.3 |
When should I use a disc magnet?
Use a disc for drilled or 3D-printed round pockets, closures, crafts and sensors. Discs are the easiest shape to glue into a hole and come in the widest range of sizes. Browse disc magnets and see magnets for 3D printing.
When should I use a block magnet?
Use a block when the contact area is flat or long, for example cabinet doors, jigs, fixtures and signs, or when a rectangular slot fits better than a round hole. Browse block magnets.
When should I use a ring magnet?
Use a ring when something has to go through the magnet: a screw, pin, rod, shaft or cable. Do not overtighten a screw on a plain ring, because neodymium is brittle; for screw mounting, a countersunk magnet with a cone-shaped hole lets a flat-head screw sit flush. Browse ring magnets.
How do disc, block and ring magnets compare?
| Shape | Best for | Mounting | Size format |
|---|---|---|---|
| Disc | Round pockets, closures, crafts | Glue into a hole or onto a surface | Diameter x height |
| Block | Flat or long contact, fixtures, doors | Glue into a slot or onto a surface | Length x width x height |
| Ring | A screw, pin or shaft through the middle | On a pin or shaft, or with a screw (gently) | Outer x inner diameter x height |
| Pot (cup) | Strong hold on one face, screw or hook mounting | Thread, screw hole or hook | Diameter x height |
For the strongest one-face hold with a built-in screw, thread or hook, look at pot magnets.
Related guides
Need help choosing? Find an exact size with magnets by size, or convert inch sizes with our magnet size chart. For larger quantities or a size, grade or coating we don't list, ask us about a custom specification.
Safety: strong magnets can pinch fingers and skin, and can chip or shatter if they snap together. Keep them away from pacemakers and other medical implants. Our products are not toys: keep small magnets out of the reach of children. See our magnet safety page.
Questions and answers
Which is stronger, a disc or a ring magnet?
For the same outer size and grade, a disc is stronger on flat steel, because the hole in a ring removes magnet material and contact area.
When should I use a ring magnet instead of a disc?
When a screw, pin, rod, shaft or cable has to pass through the magnet. For screw mounting, a countersunk magnet lets a flat-head screw sit flush.
Are block magnets stronger than disc magnets?
It depends on the size. A block has more material than a disc of the same width and height, so it often holds more, but compare the listed pull force for the exact sizes.
How are ring magnet sizes written?
As outer diameter x inner diameter x height, for example 20 x 10 x 10 mm.
Where are the poles on a disc magnet?
On most disc magnets the poles are on the two flat faces, because they are magnetised through the thickness. Diametrically magnetised discs have the poles on the curved sides.