A pot magnet (usually called a cup magnet in the US) is a neodymium magnet set in a steel cup that concentrates the magnetic field on the open face, so it holds on that face and is easy to screw, bolt or glue in place. Our pot magnets with a supplier value list pull forces from approx. 9.9 lb (4.5 kg) to approx. 235.9 lb (107 kg), measured straight off thick steel.
How does a pot magnet work?
The steel cup around the magnet guides the field to the open face, so both poles are on one side. The back and sides are hardly magnetic. The cup carries the screw hole, thread or stud, which makes a pot magnet easy to mount on almost any material. Because the field is concentrated on the face, pot magnets are especially sensitive to air gaps: paint, dirt or an uneven surface reduce the hold more than with a plain magnet. Source: our technical data page, sections 4 and 5.
Which types of pot magnet are there?
The type is about how you fix the magnet. Our pot magnets by mounting type:
| Type | How you mount it | Products | Supplier values (lb) | Calculated estimates (lb) |
|---|---|---|---|---|
| Countersunk hole | Flat-head (countersunk) screw from the front | 11 | 12.1–235.9 | – |
| Threaded bush | Screw or bolt into a threaded sleeve at the back | 11 | 9.9–160.9 | approx. 46.3, calculated |
| Internal thread | Screw or bolt into a threaded hole at the back | 8 | 9.9–33.1 | approx. 9.9–88.2, calculated |
| Threaded stud | Threaded pin at the back: through a hole, with a nut | 8 | 9.9–39.7 | approx. 15.4–88.2, calculated |
| For gluing | Glue into a hole or onto a surface | 6 | 9.9–39.7 | approx. 15.4–37.5, calculated |
| Rubber-coated | Thread or stud, rubber jacket protects surfaces | 8 | 28.7–121.3 | – |
| Channel (rectangular) | Rectangular steel channel, countersunk screw holes | 8 | – | – |
| With handle | Hand-held: lift, position and pull off | 7 | – | – |
Calculated estimates (12 products) are for pot magnets without supplier data: each is based on our supplier values for pot magnets of the same or nearly the same size, is never higher than them, and is labelled "calculated" on the product page. "–" means this guide lists no value of that kind; for 15 of our 67 neodymium pot magnets, mainly the pots with a handle and the channel magnets, check the product page.
How strong is a pot magnet?
Pull force generally grows with the diameter and height of the cup. Supplier values from our product pages:
These are straight-pull values on a thick, flat, bare steel plate. On thin sheet metal, painted steel or a vertical surface, a pot magnet holds noticeably less. See magnet pull force explained.
Which mounting type should I choose?
- Countersunk hole: for screwing onto wood, plastic or a wall; the flat-head screw sits flush with the face. Popular for cabinet doors and fixtures, see magnets for furniture and cabinets.
- Threaded bush or internal thread: to bolt the magnet to a part, a bracket or a handle from behind. M4 is a metric thread with a 4 mm diameter, so it doesn't take inch screws such as #8 or 1/4"-20; use metric screws of the size in the product name.
- Threaded stud: to pass through a hole and fix with a nut.
- For gluing: to set flush into a drilled hole; see how to glue neodymium magnets.
- Rubber-coated: for painted surfaces, vehicles and outdoor use; the rubber protects the surface and resists sliding but holds less than an uncoated pot of the same size.
You can't drill or machine a neodymium magnet yourself, so a pot magnet or a countersunk magnet is the way to screw a magnet down.
Are hook and eyebolt magnets pot magnets?
They work the same way: a magnet in a steel housing with a hook or eyebolt fitted to the back. See hook and eyebolt magnets and, for retrieving objects from water, fishing magnets.
Related guides
Need help choosing? Browse all mounting magnets. For larger quantities or a size, grade or coating we don't list, request a quote. In-stock orders ship from US stock the same working day and arrive in about 5 business days; shipping is $5.99 under $50 and free from $50 (see US shipping).
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
What is the difference between a pot magnet and a cup magnet?
There isn't one. Both names describe a magnet set in a steel cup; "cup magnet" is the more common term in the US.
How much weight can a pot magnet hold?
Our pot magnets with a supplier value list approx. 9.9 lb (4.5 kg) to approx. 235.9 lb (107 kg), measured straight off thick steel. In real use, on thinner or painted steel or with a sideways load, they hold noticeably less.
Which side of a pot magnet is magnetic?
The open face. The steel cup guides the field to that face, so the back and sides are hardly magnetic.
Why does my pot magnet hold less on a painted surface?
Paint acts as an air gap, and pot magnets are especially sensitive to air gaps because their field is concentrated on the face.
Can I screw a pot magnet onto wood?
Yes. Use a countersunk pot magnet with a flat-head screw, or a version with an internal thread or bush and a bolt from behind.
Are pot magnets waterproof?
No. Our standard pot magnets have a nickel-plated magnet and aren't suitable for permanent exposure to water. For outdoor use, choose a rubber-coated pot magnet.
What does M4 mean in a pot magnet's name?
It's the metric thread size of the bush, internal thread or stud: M4 takes a 4 mm metric screw.