Most hobbyists over-buy one size and then discover it fits nothing. Magnet sizing is not really about strength — it is about what will physically fit inside a 2mm shoulder socket without punching through the other side. This guide gives you the sizes that work, the drill bits that match them, and how many you actually need.
What size magnets do most hobbyists use?
For 28–32mm infantry, the workhorse sizes are 1mm x 1mm and 2mm x 1mm discs. Larger models — monsters, cavalry, vehicles and anything on a 50mm base or bigger — usually take 3mm x 1mm or 3mm x 2mm. If you buy only two sizes, buy 2x1mm and 3x2mm.
Everything below is written around plastic and resin models in the Warhammer 40,000 range and the base sizes they typically use, but the sizing logic is dimensional rather than game-specific — it transfers unchanged to any 28–32mm system.
Magnet size chart by joint
| Job | Magnet size | Drill bit | Notes |
|---|---|---|---|
| Infantry arms and shoulders (25–32mm bases) | 1x1mm or 2x1mm | 1mm / 2mm | 2x1mm is far easier to handle. Use 1x1mm only where the socket is genuinely too thin. |
| Infantry weapon swaps (backpacks, hand weapons) | 2x1mm | 2mm | Enough hold for a plastic weapon arm; light enough not to sag. |
| Character heads and helmets | 1x1mm | 1mm | Neck cavities are shallow. Drill the head first — it is the part you can least afford to blow out. |
| Cavalry and 40–60mm models | 3x1mm | 3mm | Good balance of hold and cavity depth. |
| Monster and vehicle joints, turrets, wings | 3x2mm or 5x2mm | 3mm / 5mm | Heavier resin arms need the extra thickness, not just diameter. |
| Base to movement tray or steel shelf | 3x1mm or 5x1mm | 3mm / 5mm | Sits in the recess under a standard base without raising the model. |
Check the individual model rather than trusting the chart blindly — sockets vary between kits, and older plastics are often thinner than recent ones.
Does diameter or thickness matter more?
Diameter does more work than thickness. Going from a 2mm to a 3mm disc at the same thickness roughly doubles the contact face and the hold, whereas going from 1mm to 2mm thick adds far less. Reach for a wider magnet before you reach for a thicker one — then check the socket can take it.
What drill bit size should you use?
Match the bit to the magnet diameter exactly — a 2mm magnet wants a 2mm bit. Plastic flexes just enough to give a tight friction fit, which holds the magnet square while the glue cures. Do the drilling by hand in a pin vice, not a rotary tool: a powered bit generates enough heat to melt the plastic and open the hole out oversize in about half a second.
Drill slightly deeper than the magnet is thick. A magnet standing proud of the surface stops the joint closing and leaves a visible gap.
What size magnets for bases and movement trays?
For a 25mm or 32mm base, a single 3x1mm magnet in the underside recess is enough, paired with steel paper or a steel sheet in the tray. For 40mm and larger, step up to 5x1mm or use two 3x1mm magnets set apart from each other — two spaced magnets resist twisting far better than one central magnet of double the strength.
The limiting factor is the depth of the recess under the base rather than the diameter of the base itself, so measure before ordering. Our step-by-step guide to magnetising miniature bases covers depth measurement, packing out deep recesses and testing the hold.
Do you need magnets on both sides of a joint?
No, and often you should not. Magnet-to-steel gives roughly half the hold of magnet-to-magnet, but it removes polarity mistakes completely — any arm fits any socket, in any orientation. For arms and weapon options, magnet-to-magnet is worth the care. For bases and trays, magnet-to-steel is the sane choice.
How many magnets will you actually need?
Budget roughly four per infantry model if you are magnetising both arms (two arms, two sockets). A ten-model squad with swappable arms is around 40 magnets. A character with a head, two arms and a backpack option is six to eight. Packs of 100 sound generous until you start; buy 200 of your main size and you will not stop halfway through a squad.
What are the most common sizing mistakes?
- Buying one size for everything. A 3x2mm magnet will not fit an infantry shoulder, and a 1x1mm will not hold a resin monster arm.
- Drilling before test-fitting the joint dry. Some sockets are thinner than they look and blow out through the back.
- Going too strong on thin plastic. An overpowered magnet on a slim wrist joint can snap the part when someone pulls it off.
- Forgetting the base recess depth. A magnet that sits proud rocks the model and undoes all your work.
- Measuring by eye. A cheap digital calliper costs less than a wasted pack of magnets.
Are neodymium magnets safe to have around the house?
Handle them like small sharp tools, not like beads. Neodymium magnets are genuinely dangerous if swallowed — two or more can attract through the wall of the gut and cause serious internal injury — so keep loose magnets in a closed pot and well away from children and pets. They also lose strength permanently above roughly 80°C, so avoid leaving magnetised models in a hot car, a loft or a sunny window.
Independent guide published by Blubbercove Ltd/WarSplay. This article is not affiliated with, sponsored by, endorsed by, authorised by or licensed by Games Workshop Limited. Warhammer 40,000 is a trade mark of Games Workshop Limited.
Related guides
- How to Magnetise Warhammer 40,000 Arms and Weapons — the drilling and polarity method, step by step.
- How to Magnetise Warhammer 40,000 Miniature Bases — fitting magnets under a base for transport and storage.
- Which Magnet Grade Do You Need? N35 vs N52 — what the N-number means and when it is worth paying for.