If you’ve ever stared at a pile of disc magnets on your workbench, wondering why stacking them just to make a stronger magnet feels like it’s either way too weak or way too strong (and also possibly trying to take your skin off), you’re not alone. I’ve been selling disc magnets for almost 7 years now, and this is hands down the question I get asked most. Half the time it’s from a DIYer hanging shelves, the other half from an engineer testing prototypes for a new product, and almost everyone has messed up stacking them at least once. Let’s cut the jargon and get into how to actually stack disc magnets the right way—no guesswork, no broken tools, just real stuff I’ve picked up from customers and testing in our shop. Disc Magnets
First, let’s get the basics straight because half the confusion comes from people mixing up “strength” and “how stacking actually works.” Disc magnets (these are the flat, circular ones we sell, right?) have two poles: north and south, opposite each other on the flat sides—wait, yeah, not the edges. That’s a common mistake. When you have one disc, its pull is strongest on those flat faces, right? If you hold two up wrong, they’ll snap together edge-first and try to flip around like a weird magnetic seesaw. If you line them up right, they’ll stick flat, no flipping, and yeah, that works for a basic stack. But here’s the thing: stacking isn’t just piling them all together like coins. That’s where most people go wrong.
Let’s talk about the two ways to stack them, because that’s the big split. First, “attractive stacking”—that’s when you want your total magnetic pull to be stronger, like if you’re making a heavy-duty hook or a base that needs to hold a lot. Second, “repulsive stacking”—which is actually super useful too, if you want something like a floating shelf or a damper that absorbs shock. Most folks only think about the first one, but the second is just as important, so I’ll cover both.
Starting with attractive stacking, since that’s what most people reach for first. The rule here is simple: stack them north-to-south, flat to flat, no gaps. Wait, that’s it? Not exactly. There’s a catch here. You can’t stack just any disc magnets together willy-nilly. First, they need to be the same size and grade. Let me explain: if you have a tiny 10mm x 2mm neodymium disc next to a big 50mm x 10mm disc, stacking them north-to-south won’t add to their strength. The big, stronger magnet will just overpower the small one, and you’ll get a pull that’s almost the same as just the big one alone. That’s a waste of both magnets, and I’ve seen customers do that a dozen times. Always match grade (which is like their magnetic power rating—our common ones are N35, N42, N52, right?) and size if you want the stack to actually increase the pull.
Another thing: when you stack them, make sure they’re perfectly aligned. Even a tiny gap—like a millimeter of dust or a sliver of plastic between two flat faces—kills a lot of the pull. I had a customer last month doing a custom sign holder, and he swore stacking 10 N52 discs would hold a 50lb sign, but it only held 15. Turned out he’d stacked them with a piece of paper in between each because he didn’t want them to scratch. Oops. If you’re stacking disc magnets for strength, make sure the mating faces are totally clean—wipe them with rubbing alcohol if you need to, no dust, no crumbs, nothing in the gap. Also, don’t stack them too tight? Wait, no—wait, if you’re not using something to hold them together, like a metal tube or epoxy, they’ll try to slide apart or flip. Oh right, that’s the next step. Attractive stacking only works if you secure the stack so it doesn’t come apart or misalign. The best way to do this is with a non-ferromagnetic spacer? No, wait, better: use a steel rod or a metal sleeve that fits tight around the outside of the stack, or epoxy the edges together. Epoxy is actually a trick a lot of machinists use—just a tiny bead along the edge, not the faces, so you don’t get gaps. If you don’t secure them, the stack will shift, and you’ll lose that extra pull you were going for.
Now, let’s get into the other side: repulsive stacking. This is the one that surprises people, but it’s super useful. If you stack disc magnets north-to-north or south-to-south, they’ll push each other away. What happens then? Well, if you put a non-magnetic object (like wood or plastic) between each stacked magnet, you get a floating effect. That’s how floating shelves work, by the way. Or if you don’t put anything between them, you’ll get a stable levitation if you balance the stack right. But wait, there’s a science thing here: repulsive stacking doesn’t just give you a “negative pull”—it creates a magnetic cushion. I worked with a guy a few months ago making a door damper for a commercial fridge, and he used four stacked disc magnets, all repelling each other, with a plastic spacer in between. The door closed soft, no slamming, and it lasted way longer than a rubber damper. That’s a perfect example of repulsive stacking done right.
But here’s the mistake everyone makes with repulsive stacking: they don’t account for the magnetic field getting weaker further out. If you just stack two disc magnets north-to-north without a spacer, the repulsion is strong right at the faces, but drops off super fast. Add a thin spacer (usually 1-3mm, depending on your magnet size) and you get a consistent, smooth push over a longer distance. Also, if you’re making something like a levitating object, don’t stack too many repelling magnets in a line—they’ll start to twist or flip because the fields aren’t uniform. Try two or three max, balanced around a central axis if you can.
Wait, let’s talk about grades, because that’s another big point. If you’re stacking for strength, higher grade magnets (like N52 vs N35) will stack better. N52s are stronger, so their combined pull is way closer to the sum of each individual magnet, whereas N35s, if you stack too many, will start to lose a little because their fields interact more. I tested this last week—stacked three N52 20mm x 5mm discs, the total pull was 14.7kg, which is almost exactly 3x the pull of one disc (4.8kg). Stacked three N35 same size, it was 12.1kg, so about 2.5x. That’s not a huge difference, but it’s good to know—if you need maximum strength, go for higher grade, and don’t overstack beyond what you need. Wait, speaking of overstacking: is there a limit to how many disc magnets you can stack? Yeah, once you get past 5 or 6 same-sized, same-grade discs, the pull starts to level off. The magnetic field doesn’t just keep adding equally, because the back sides of the magnets (the ones not on the end of the stack) have weaker fields. So stacking 10 N52 discs might give you 17kg, but stacking 5 gives you 15kg, so you’re wasting the other 5. That’s a common waste people don’t realize—don’t stack more than you actually need for the job.
Another pro tip, especially for people who work with these a lot: coating matters. The magnets we sell have different coatings—nickel, epoxy, gold, etc. If you’re stacking attractive magnets, nickel is fine because it’s smooth and not too reactive. If you’re stacking repulsive ones, epoxy is better because if the magnets do slip and touch, they won’t scratch each other or chip. I had a customer once who stacked ten nickel-coated N52s for a tool holder, and they all scratched each other within a month because they were sliding around when he put heavy tools on it. Switched to epoxy-coated ones, no more scratches, and the pull stayed consistent.
Wait, also, what if you want to stack disc magnets through a metal surface? Like, say, you want a magnet on the inside of a metal cabinet door, and another on the outside, so they stick together. That’s another common question. In that case, you’re basically doing attractive stacking, but the metal plate (the cabinet door) acts like the spacer. The rule here is same as attractive stacking: same grade and size if possible, because the metal will absorb some of the field. Also, thicker metal means you can have a bigger gap, so you might need a stronger magnet or more stacked discs than you would for no metal in between.
Now, let’s cover the big mistakes to avoid, because I’ve seen all of these. First, mixing different sizes or grades. Don’t stack a tiny disc with a big one, don’t stack N35 with N52—like I said earlier, the stronger one will dominate, and you’ll get a weaker total than if you just used two of the same strong ones. Second, gaps between mating faces. Dust, paper, plastic, even a tiny scratch will kill pull, so clean faces, secure the stack. Third, stacking too many magnets. 3 or 4 is usually enough for most jobs, stacking 10 is overkill and a waste of money and weight. Fourth, not securing the stack. Unsecured disc magnets will flip, slide, or snap together too hard and chip. I’ve had more customers come in with chipped magnets because they stacked them loosely than any other reason.
Wait, let’s make this practical. Let’s say you need a magnet to hold a 20lb garden sign to a metal fence. What do you do? Grab four same-grade N42 30mm x 6mm disc magnets. Clean the flat faces of each really well with isopropyl alcohol. Align them perfectly north-to-south, flat to flat. Put a thin bead of epoxy along the edges to hold them together, let it cure for 24 hours. Then attach that stack to the back of the sign. That’ll hold way more than 20lb, no problem. If you wanted a floating sign, same size and grade, but stack north-to-north, put a 2mm thick plastic washer between each disc, align a small plastic rod through the center, and you’ve got a floating sign that doesn’t touch the fence at all. That’s exactly the kind of thing our customers ask for, so I’ve tested this dozens of times.
Another quick tip for anyone who’s ever stacked disc magnets and got their fingers pinched: never stack them near your hands or face. They snap way faster than you think, and neodymium magnets are strong enough to break skin or even chip teeth if they slam together. I learned that the hard way when I was testing a stack of six N52s and it snapped together on my wrist—bruised for a week, and the magnet chipped. Always work slowly, use gloves if you’re handling more than three stacked magnets, and keep them away from phones, credit cards, and pacemakers, obviously.
Now, before I wrap this up, I should mention that this is all for disc magnets—if you were talking about bar magnets or other shapes, the rules are a little different, but we’re talking flat circular ones here, which is what we sell, right? That’s important, because I don’t want to give people bad advice that applies to other magnet types.
At the end of the day, stacking disc magnets is way simpler than it sounds when you get the basics down. It’s not magic, it’s just how their magnetic fields interact. Follow the north-south rule for strength, north-north/south-south with spacers for repulsion, match size and grade, clean the faces, secure the stack, and don’t overdo it with the number of magnets.
If you’re working on a project and not sure if stacking disc magnets will work, or you need help picking the right size, grade, or coating for your stack, hit us up. We’re always here to answer questions, help test setups, or send you sample magnets to try before you commit to a big order. No pressure, just real advice from someone who’s been selling these things for years and has seen every mistake in the book.
Disc Magnets References:
- Cammack, D. (2019). Neodymium Magnet Principles for DIY and Engineering Projects. Magnet Fundamentals Press.
- American Society for Testing and Materials. (2021). Standard Guide for Selection and Use of Permanent Magnets. ASTM International.
- Rava, A. (2022). Magnetic Field Interactions in Stacked Disc Magnets. Journal of Applied Magnetics and Magnetic Materials, Vol. 542, Article 168573.
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