The 32mm System: One Number That Runs Through Every Cabinet You Build

Ask most cabinet makers why their shelf pin holes are spaced the way they are, and a lot of them can't tell you. It's just how the jig was set up when they started. But there's a real reason behind that spacing, and once you see it, it explains a whole stack of other decisions in the shop too — why certain hinges fit certain holes, why shelf pins from a cabinet you built five years ago still work today, why your drilling jig looks the way it does and not some other way. None of this is complicated once someone actually lays it out. It's just never been written down anywhere most people would see it, so it gets passed along as a habit instead of a rule, and habits are easy to copy without ever questioning why they work.

What the 32mm system actually is

It's a hole pattern, not a product you buy. Cabinet sides get drilled with 5mm holes spaced 32mm apart, running in vertical lines up and down the panel, usually starting a fixed distance from the bottom edge. Hinges mount into two of those holes. Shelf pins drop into any of them along the same line, and cam locks for knock-down cabinets use that same spacing too. You'll usually see two or three vertical rows of holes on a typical side panel, front, back, and sometimes a middle row, depending on how deep the cabinet is and how many fixing points the hardware calls for.

It's one drilling pattern doing three or four different jobs, which is really the whole point of it. And it's not just a kitchen thing either — wardrobe builders, closet shops, and office furniture makers all build on the same grid, because the hardware they're buying off the shelf is made to fit it, regardless of what the cabinet is actually for. Buy a hinge from a big hardware supplier anywhere in the world and odds are good it's drilled to this same spec, which is exactly why the system spread so far beyond where it started.

Where the number 32 actually came from

It's not a clever ratio or some bit of design theory someone worked out on paper. It's mechanical. Early multi-spindle line-boring machines had gearing between each drill bit, and 32mm was roughly the closest those spindles could physically sit next to each other without the gears clashing. The system dates back to just after the Second World War, when European shops were rebuilding production lines and needed a spacing every machine builder could agree on.

So the machines got built around 32mm first, and hinges, shelf pins, and knock-down hardware got designed to fit the machines afterward. The hardware followed the tool. That's backwards from how it feels today, when you're the one buying hinges off a shelf and assuming someone designed the spacing on purpose. But the standard caught on everywhere, which is why a Blum hinge, a Grass hinge, and a cheap no-name one from a wholesaler all still land on the same holes, even though none of those companies ever had to agree on anything directly.

The 37mm line, and the 35mm cup that sits on it

Most shops run their main vertical row of 5mm holes 37mm back from the front edge of the panel. That's the reference line both the hinge cup and the shelf pins sit on, and it's the number that controls whether a door looks right once it's hung. Move that line even slightly and every door on the job ends up slightly off in the same direction, which is much harder to spot cabinet by cabinet than it is once the whole run is standing in a kitchen.

The hinge cup itself isn't one of those 5mm holes though. It's a separate 35mm diameter hole, bored to a set depth, usually somewhere around 11 to 13mm depending on the hinge brand you're using. That hole sits on the same 37mm line, but it gets drilled with a completely different bit, on a different setting, which is exactly where mistakes tend to creep in when a shop is switching between jobs.

Get either number wrong and you'll see it right away. Move the 37mm line and the hinge cup sits too close to the edge, or too far in, and the door won't sit flush. Get the cup depth wrong and the hinge either sits proud, so the door won't close properly, or too deep, so the hinge arm binds when you swing the door. It's worth dialling in that depth stop on a scrap piece before you touch a real panel, every single time you switch hinge brands, because 2mm of extra depth is enough to turn a perfectly good hinge into a warranty call.

Why hinges and shelf pins share the same holes

This is the part that actually saves you time on the bench. Because hinges and shelf pins both sit on the same 32mm grid, you don't need two separate drilling setups for one cabinet side. Drill the line once, and every hinge position and every shelf position already exists on that panel, ready for whichever piece of hardware ends up going in.

You're not going back later to add a second row of holes just so the shelves can be adjustable. One pass through the jig covers both jobs, and that's time you're not billing a client for twice. On a kitchen with a dozen cabinets, that one shortcut alone can save you the better part of an afternoon.

• One jig, one pass, covers hinge boring and shelf pin holes together
• Shelf heights stay fully adjustable without ever redrilling the panel
• Cam lock hardware for flat-pack cabinets drops into the exact same holes
• Replacement hardware years later still fits, because the grid never changed
• A stripped or damaged hole can often be swapped for the next one on the same line
• Hardware from a different supplier usually still lines up, because they built to the same standard

The symmetry rule that keeps shelves sitting level

Here's a trick worth stealing if you don't already use it. The gap from your lowest hole to the bottom of the panel should match the gap from your highest hole to the top. It sounds like a small detail, but it's what makes the whole system predictable instead of something you have to remeasure every time a new panel comes through.

That symmetry means you can flip a panel end for end and the holes still land in the right place, which matters more than you'd think when you're working fast and grabbing panels off a stack without checking which side is which. It also means two cabinets built to slightly different heights can still share shelf pin and hinge positions without you doing fresh math for every single job that comes through the shop, which is exactly the kind of repeat setup that eats a shop's time if nobody's standardised it.

What happens when a shop ignores it

You see this most on older kitchens or cheap flat-pack jobs where someone free-handed the hinge positions instead of working off a proper grid. Shelves wobble because the holes aren't level with each other. Hinge cups sit crooked from one door to the next on the same run, so the doors never quite line up even after you've adjusted every screw you can reach. Some shops try to fix it with packing shims instead of fixing the holes, which papers over the problem for a while but never actually solves it.

Replacement hardware from a different supplier doesn't line up with the existing holes either, so the homeowner is stuck with whatever brand was used the first time, or they're paying someone to redrill the whole cabinet from scratch. It's also the reason a fitter can walk into almost any kitchen built on standard European hardware and know roughly where the holes will be before they've even opened a door. That's not luck. That's the grid doing its job quietly in the background, the way it's meant to, and it's the same reason a cabinet built this year can still take a hinge bought a decade from now.

Tools that make the grid easy to hit

You don't need a full line-boring machine to build on this system. A shop-made jig with dowel pins set on 32mm centres does the job fine for small runs and one-off jobs, and plenty of shops run on exactly that for years before upgrading to anything fancier. The main thing is building the jig once, checking it carefully, and then never letting anyone in the shop drill off a different setup just this once.

Festool's LR 32 rail system is a common upgrade once volume picks up, since it rides along the panel edge and keeps every hole on the same line without you measuring each one by hand. Multi-spindle line-boring machines go a step further again, drilling a whole row in one pass once a shop is doing enough volume to justify the cost. Either way, the goal stays the same: get every cabinet side on the same grid, so hardware stays interchangeable years down the line, no matter who ends up servicing the cabinet after you.