How strong is a neodymium magnet?
Short answer: neodymium magnets are the strongest permanent magnets you can buy: approximately 5 to 10 times stronger than a regular (ferrite) magnet of the same size. A disc magnet of Ø10 x 3 mm holds approx. 2.1 kg on steel, a Ø20 x 5 mm approx. 7.4 kg and a Ø40 x 20 mm approx. 49 kg. That is the holding force under ideal conditions; in practice it is often half or less.
Holding force per size (disc magnets, N48)
Stated holding force of our NiCuNi disc magnets, measured perpendicular to a thick, flat steel plate:
| Dimensions | Holding force (approx.) | Comparable to |
|---|---|---|
| Ø5 x 2 mm | 0.6 kg | a few A4 sheets on a whiteboard |
| Ø8 x 3 mm | 1.4 kg | a liter of milk |
| Ø10 x 3 mm | 2.1 kg | closing a cabinet door |
| Ø10 x 5 mm | 3.1 kg | a small hammer |
| Ø15 x 5 mm | 4.3 kg | a full grocery bag (light) |
| Ø20 x 5 mm | 7.4 kg | a crate with 6 bottles and more |
| Ø20 x 10 mm | 12 kg | a full bucket of water |
| Ø30 x 10 mm | 22 kg | a piece of carry-on luggage, twice |
| Ø40 x 20 mm | 49 kg | an adult dog |
You can find all sizes and values in the disc magnets, the block magnets and the pot magnets.
What determines how strong a neodymium magnet is?
- Thickness and diameter: the biggest factor. A Ø20 mm disc holds approx. 3.1 kg at 2 mm thickness, approx. 7.4 kg at 5 mm and approx. 12 kg at 10 mm. Thicker makes a big difference, until the thickness is approximately equal to the diameter.
- Quality (N35 to N52): an N52 is 20 to 40% stronger than an N35 of the same size. See what does N35, N42, N48 and N52 mean?
- Distance: the force drops off quickly. For small magnets, a distance of 1 mm (paint, foil, cardboard) often already halves the holding force.
- The substrate: thin steel (under approx. 2 – 3 mm), stainless steel, cast iron or a rough surface provide less holding force. On aluminum, copper and most types of stainless steel, a magnet does not work.
- Direction of the load: on a vertical wall, a magnet slides already at 15 – 25% of the stated holding force. See holding force, pulling force and working load.
- A steel pot: a pot magnet is often several times stronger at the same diameter. See why are pot magnets so strong?
Neodymium compared to other magnets
| Material | BHmax (energy product) | Max. temperature | Typical use |
|---|---|---|---|
| Neodymium (NdFeB) | 33 – 53 MGOe | 80 °C (special grades up to 200+ °C) | strong small magnets, motors |
| Samarium-cobalt (SmCo) | 16 – 32 MGOe | 250 – 350 °C | high temperatures, aerospace |
| AlNiCo | 1.5 – 10 MGOe | 450 – 550 °C | sensors, guitar pickups |
| Ferrite (ceramic) | 1 – 4.5 MGOe | approx. 250 °C | refrigerator magnets, speakers |
| Rubber magnet (flexible) | 0.6 – 1.5 MGOe | approx. 70 °C | magnetic foil, advertising |
Why is neodymium so strong?
Neodymium magnets consist of the crystal compound Nd₂Fe₁₄B. This combines many iron atoms (high magnetization) with a crystal structure that strongly fixes the magnetization in one direction. Because of this, the material can deliver much more magnetic energy at the same size than ferrite. The material was developed simultaneously by Sumitomo (Japan) and General Motors (US) in 1982 – 1984. Read more about the material in what is neodymium and where does it come from?
Frequently asked questions
How many kilos can a neodymium magnet carry?
From a few grams (Ø2 x 1 mm, approx. 0.13 kg) to hundreds of kilos (block 100 x 100 x 50 mm, approx. 350 kg). Calculate for a practical load with at most a third to half of the stated holding force, and on a vertical wall even less.
Are neodymium magnets dangerously strong?
Large neodymium magnets can strike each other or steel with great force, pinch fingers and splinter. Keep them away from children, pacemakers and bank cards. Read working safely with magnets.
Is a magnet with a higher Gauss value stronger?
Not necessarily. Gauss says something about the field at one point, not about the holding force. See what is Gauss and Tesla?
Read also
- How is the holding force of a magnet determined?
- Which disc magnet do you choose?
- Do magnets work through wood, glass and plastic?
Need help choosing? Use the Magnet Advisor or contact us.
