Can magnets work through wood, glass, and plastic?
Short answer: yes. Wood, glass, plastic, cardboard, textiles, aluminium and most types of stainless steel let a magnetic field through virtually unhindered. The problem is not the material but the distance: the force drops off quickly. With small magnets, 1 mm of distance often already halves the holding force; through 5 mm of material often only 10 – 25% remains. So through a thick material you use a larger or thicker magnet, or let two magnets attract each other instead of a magnet and a steel plate.
How much force remains? (indicative)
| Distance (material thickness) | Small magnet (Ø10 x 3 mm) | Larger magnet (Ø20 x 10 mm) |
|---|---|---|
| 0 mm (directly on steel) | 100% | 100% |
| 1 mm | approx. 40 – 55% | approx. 70 – 80% |
| 2 mm | approx. 25 – 35% | approx. 55 – 65% |
| 5 mm | approx. 5 – 10% | approx. 25 – 35% |
| 10 mm | < 3% | approx. 10 – 15% |
Rule of thumb: the thicker the magnet relative to the distance, the more force remains. A magnet at least as thick as the material it has to work through usually works well. Always test with the actual material.
Magnet + magnet or magnet + steel?
Through a thick panel, two magnets attracting each other work much better than a magnet on a thin steel plate. A thin plate (0.5 – 1 mm) saturates quickly and only captures part of the field. With two magnets, pay attention to the poles: the north pole of one must face the south pole of the other. See why do magnets attract each other?
Per material
- Glass (whiteboard, glass board): a glass board is 4 – 6 mm thick with a steel plate behind it. Ordinary ferrite magnets work poorly there; choose strong neodymium magnets of at least Ø10 x 5 mm or larger pot magnets.
- Wood: a magnet in a milled hole with a thin layer of wood in front (1 – 2 mm) stays invisible and still works well. Ideal for cabinet doors and hidden closures. See magnets for interior construction.
- Plastic and 3D prints: leave a 0.4 – 0.8 mm wall between the magnet and the outside. See magnets for 3D-printed applications.
- Fabric and leather: no problem; that is what sew-in magnets and race number magnets are made for.
- Aluminium and stainless steel: let the field through, but the magnet will not stick to them.
Which materials does a magnet work poorly through?
Only ferromagnetic materials such as steel and iron (and mu-metal) divert the field. A steel plate between two magnets therefore acts as a shield, not as a pass-through. Thick steel cabinets and metal frames can shield a magnet on the other side.
Frequently asked questions
Does a magnet work through a fridge door?
A fridge door is made of steel, so a magnet sticks to it well but does not work through it. The steel is thin, though (approx. 0.6 mm), so a strong magnet only achieves part of its stated holding force there.
Which magnet for a glass memo board?
Choose neodymium magnets of at least Ø10 x 5 mm, or 10 mm ball and cube magnets. For heavy papers a pot magnet.
How thick can the wood be?
With two Ø20 x 5 mm magnets, a closure still works fine through 3 – 5 mm of wood. For more than 10 mm, choose larger magnets or make the wood thinner at that spot.
Read also
Need help choosing? Use the Magnet Advisor or contact us.
