Is Magnet-to-Magnet Stronger Than Magnet-to-Steel?
When they touch, about the same. A magnet pulled straight off thick steel holds about its listed pull force, and a pair of identical magnets touching north to south holds about the same, not double. Add any gap, or use thin steel, and the pair wins. Through 1/8 in of wood or fabric, two 1/2 × 1/8 Inch N52 discs hold about 2.1 lb, while one disc on thick steel holds about 0.9 lb. Steel strike plates still win on cost, easy alignment and having no polarity to get wrong.
- Touching thick steel
- About equal: both near one magnet's rating
- Through a 1/8 in gap
- The pair holds about 1.7 to 2.4 times more
- Thin sheet steel
- The pair holds much more
- Two magnets together
- About one magnet's rating, not two
- Alignment
- A pair self-centers; steel holds anywhere
Why They’re Equal When Touching
Steel gathers a magnet’s field so well that the magnet pulls on it as if a mirror image of itself were hiding behind the steel’s surface. That reflection behaves like a second, identical magnet. When the magnet touches the steel, its reflection “touches” it too, so the pull equals that of a real pair in contact.
That’s also why our listed pull force, which is measured straight off a thick, ground steel plate, is a good estimate for a touching pair of the same magnet. Real steel is never quite a perfect mirror, so a touching pair can measure slightly higher than the same magnet on steel.
Why a Pair Wins Through a Gap
The mirror image sits as far behind the steel’s surface as the magnet sits in front of it. So a gap of 1/8 in between a magnet and steel acts like 1/4 in between two magnets. A real second magnet on the other side of the same gap is only 1/8 in away, and magnetic pull drops off fast with distance.
Calculated straight pull through a gap, from our magnetic model:
| Gap | 1/2 × 1/8 Inch pair | 1/2 × 1/8 Inch on steel | 1 × 1/4 Inch pair | 1 × 1/4 Inch on steel |
|---|---|---|---|---|
| None | 8.15 lb | 8.15 lb | 33.7 lb | 33.7 lb |
| 1/32 in (paint, paper, a fabric cover) | 4.9 lb | 3.5 lb | 24.9 lb | 20.3 lb |
| 1/16 in (felt, cardboard, a sticker) | 3.5 lb | 2.1 lb | 20.3 lb | 14.6 lb |
| 1/8 in (thin wood, acrylic, tile) | 2.1 lb | 0.9 lb | 14.6 lb | 8.6 lb |
| 1/4 in (glass, thin plywood) | 0.9 lb | 0.2 lb | 8.6 lb | 3.7 lb |
The bigger the gap compared with the magnet, the bigger the pair’s advantage: for these two sizes, about 1.4 to 1.7 times at 1/16 in and 2.4 to 4 times at 1/4 in. For panels and walls, see magnets through wood, drywall or glass.
Thin Steel Changes the Picture
Steel can only carry so much magnetism before it saturates. A thin strike plate, a fridge door or the side of a filing cabinet fills up long before a strong magnet’s field runs out, so the extra field leaks out the back instead of adding pull. On thin sheet steel, expect a strong magnet to hold about half its rating or less. A second magnet doesn’t have this limit, because it brings its own field. For the best hold from a steel plate, use the thickest one your design allows; see using strike plates.
Two Magnets Don’t Double the Strength
A common surprise: stick two identical magnets together and the pair holds about one magnet’s rating, not two. Each magnet is pulling on the other, so you’re measuring one connection. To hold more:
- Use a bigger or thicker magnet. Thickness adds pull, with gains shrinking once the magnet is about as thick as it is wide.
- Stack magnets on one side. A stack acts like one thicker magnet; see stacking magnets.
- Add more magnets, spaced apart. Separate connections roughly add up.
For the most pull, pair identical magnets. A pair is limited by its smaller magnet, so a much bigger magnet on the other side won’t make a small magnet hold like a big one.
Which Should You Use?
Choose a Magnet Pair
- There’s a gap: fabric, wood, glass, a cover or a coating
- The other side is thin steel, or there’s no steel at all
- You want self-alignment, for lids, doors and hidden closures
- Check the poles: north must face south
Choose Magnet + Steel
- The two parts touch, with no gap
- You want the lower cost of one magnet and a steel disc
- Alignment varies: the magnet holds anywhere on the plate
- No polarity to get wrong
Paired Packs Make Pairs Easy
Most of our countersunk and self-adhesive magnet packs are split half north and half south, so one of each attracts.
Pairs Snap Together Hard
Two strong magnets jump together with more force than a magnet and steel at the same distance, and they can pinch skin or chip each other. Bring them together slowly and from the side.