Which block magnet do you choose?
Which block magnet is right for your project? An overview by application, from model building and small fasteners to cabinet doors, workshops, and mechanical engineering, including explanations of countersunk holes, pole orientation, epoxy, and self-adhesive versions.
When choosing the right block magnet, consider the application and holding force, not just the dimensions. Below you will find out which version is suitable for each application, when a magnet is too small, and what to pay attention to with countersunk holes, polarity, epoxy coating, and self-adhesive versions. All block magnets are made of neodymium. Want to calculate how much holding force you need? Use the calculator further down or the Magnet Advisor.
Quick selection by application
| Application | Usually suitable for | Example |
|---|---|---|
| Model making, electronics and small closures | Holding force up to approx. 1 kg | 6 x 4 x 2 mm |
| Cabinet doors, flaps, furniture making, motorhomes and caravans | Holding force approx. 4 to 10 kg | 30 x 10 x 5 mm, 20 x 20 x 5 mm |
| Workshops, tools, moulds and heavier panels | Holding force approx. 10 to 25 kg | 60 x 40 x 5 mm, 25 x 25 x 10 mm |
| Industry, clamping and machine building | Holding force from approx. 25 kg | 40 x 40 x 10 mm, 60 x 60 x 30 mm, 85 x 30 x 12 mm with stainless steel handle |
| Screw-in mounting | Version with countersunk hole | 25.4 x 25.4 x 12.7 mm plastic with hole |
| Damp environments or steel doors | Epoxy version | 80 x 20 x 2 mm epoxy |
This is a guideline. Always test with one or two magnets before ordering or installing a large batch.
Calculate how much holding force you need
Enter the weight, the number of block magnets and the substrate. The calculator shows how much holding force per magnet you need at least and displays suitable block magnets from our range. It is a guideline: always test with one or two magnets.
Why a block magnet?
A block magnet has a flat contact surface. This makes it convenient for mounting in slots and against flat surfaces, and for elongated or flat versions along an edge. A disc magnet is round; if you prefer a round shape, read Which disc magnet should you choose?.
Choose by holding force
- Under 1 kg: thin and light, for model making, electronics and small parts.
- 1 to 4 kg: small closures and removable parts, for example 10 x 5 x 4 mm: approx. 2.0 kg.
- 4 to 10 kg: cabinet doors, furniture making and motorhomes, for example 20 x 20 x 5 mm: approx. 7.8 kg.
- 10 to 25 kg: workshop, tools, moulds and heavier doors, for example 60 x 40 x 5 mm: approx. 24 kg.
- From 25 kg: professional use, for example 40 x 40 x 10 mm: approx. 40 kg. These magnets can snap hard against each other or against metal; keep your fingers away.
Note: thin block magnets (2 – 3 mm) have a high stated holding force due to their large surface, but this quickly drops off as soon as there is something between the magnet and the steel. For cabinet doors with a gap or through wood, it is better to choose a thicker size.
Countersunk hole and polarity
Block magnets with a countersunk hole are screwed in with a countersunk screw. For these versions, the product name or specifications state which pole is on the countersunk side: north pole or south pole. This is important if two magnets need to attract each other, for example a magnet in a door and a magnet in the frame.
Two identical variants repel each other. If two magnets need to attract each other, combine a north pole variant with a south pole variant. Sometimes you therefore need one of each, such as 30 x 13.5 x 5 mm north pole and south pole, or 13.5 x 13.5 x 5 mm north pole and south pole. A block magnet with a countersunk hole and a steel counter surface always works; the pole choice only matters if you place two magnets opposite each other.
Self-adhesive versions have the same polarity: pay attention to which side faces outwards when applying. Stick them on a clean, dry and flat surface. Unsure about the polarity? Contact us.
Epoxy and plastic coated
By default, our block magnets have a NiCuNi coating (nickel-copper-nickel), suitable for dry indoor spaces. Epoxy versions and plastic-coated versions offer extra protection against moisture and wear. For steel doors: read Epoxy coated magnets in steel doors.
What to pay attention to
- The holding force is a laboratory value. It is measured on a flat, thick steel plate. In practice, the actual force is lower, especially with a thin, uneven or coated surface or if there is an air gap. Read how holding force is determined. Always test.
- Quality (N35, N48, etc.). A higher number means a stronger magnet of the same dimensions. Read what N35, N42, N48 and N52 mean.
- Temperature. Our block magnets are suitable up to 80 °C. Above this temperature, the magnet can permanently lose strength.
- Jewelry. The NiCuNi layer contains nickel. Set the magnet into the jewelry so that the skin does not come into contact with it.
- Safety. Magnets are not toys and should be kept out of reach of children. Keep strong magnets away from pacemakers, electronics and bank cards.
