Gridfinity specs and dimensions explained: the 42 mm grid, 7 mm units and where the magnets go

17 September 2026

gridfinitybasics

A Gridfinity bin occupies 42 mm per unit in each direction, is 7 mm per unit tall, and its outside measures 41.5 mm per unit because each foot is drawn 0.25 mm inside the grid on every side. A 2x3 bin is therefore 83.5 x 125.5 mm on the outside and sits in an 84 x 126 mm slot on the plate. That is the whole standard in one sentence; the rest of this post is the detail I needed when I wrote the Gridfinity generator, so you do not have to dig it out of a spreadsheet. Why the grid is 42 mm in the first place is a post of its own.

Footprint: 42 mm pitch

Sizes are counted in units, not millimetres. One unit is 42 mm of plate. Bins are 41.5 mm per unit across, so a 1x1 is 41.5 mm square, a 2x2 is 83.5 mm and a 4x4 is 167.5 mm. The 0.5 mm the bin gives up is split into 0.25 mm of clearance per side, which is what lets a bin drop into a plate printed on another machine.

Plates fill beds in whole units, so the question is how many units your printer takes:

• 180 mm bed (a Prusa Mini): 4 units, 168 mm.
• 220 mm bed (an Ender 3): 5 units, 210 mm.
• 256 mm bed (a Bambu X1 or P1): 6 units, 252 mm.
• 350 mm bed (a Voron 350 or an Ender 5 Plus): 8 units, 336 mm.

Bigger drawers take several plates butted edge to edge. The bins never notice where one plate ends, because the plate is only a field of identical sockets.

Height: 7 mm units

Height is counted in 7 mm units from the very bottom of the foot to the rim. The stacking lip adds 4.4 mm on top of that and is not part of the count. The sizes people actually print:

• 2u, 14 mm: a tray for washers and SD cards.
• 3u, 21 mm: the classic small parts bin, most of my drawer is 3u.
• 6u, 42 mm: screws, cable ties, a multimeter on its side.
• 9u, 63 mm: a deep bin for tools standing up.
• 12u, 84 mm: markers and long bits.

The generator allows 2 to 18 units, and 18u is 126 mm, which is where a 1x1 bin stops being storage and starts being a vase.

The foot, from the bottom up

The foot is the part that has to be exact. Its profile, measured from the bed upward, is 0.8 mm at 45 degrees, then 1.8 mm straight, then 2.15 mm at 45 degrees again, 4.75 mm in total. The top of the foot is a 41.5 mm square with corners rounded at 3.75 mm. Every bin, from every designer, carries this exact shape under each unit of its footprint, and a plate is nothing but the negative of it repeated at 42 mm.

The lip on top of a bin uses a related profile, 0.7 mm, 1.8 mm and 1.9 mm, so the foot of the bin above nests into it. That is the trick behind stacking: a bin does not know whether it stands on a plate or on another bin.

Magnets and screws

The magnet is a 6.5 mm diameter, 2.4 mm thick disc, one in each corner of each unit, pressed into a pocket in the foot from below. Within a unit the four pockets sit 26 mm apart centre to centre. A 2x2 bin therefore has 16 pockets, and you can fill all of them or only the four outer corners; the bin sits flat either way.

If you would rather bolt a plate down, an M3 hole sits concentric with each magnet pocket, so the same corner takes a magnet, a screw, or both. My own plates are not glued or screwed at all; the bins stay put because the sockets hold them and the drawer holds the plate.

What the generator adds to the standard

The numbers above are not adjustable, on purpose. Change any of them and your bins stop fitting everyone else's plates. What you do choose is the footprint (1 to 8 units per side, 350 mm span at most), the height, the wall thickness (0.8 to 2.4 mm, default 1.2), the compartments (up to 8 by 8, each at least 12 mm wide, with a quarter-round scoop at the front), a 12 mm label ledge along the back, and whether the magnet pockets and screw holes are there at all. A plate takes only its size.

If you want a size without typing anything, the library has the ones I print most, each with the dimensions already filled in: the 1x1 bin, 3u, the 3x2 sorter with six compartments and the 4x4 baseplate. All 35 are under Gridfinity in the model library.

The bin that grew a roof

The one release that went wrong here was 1.237.1, the same day the first post about the generator went out. Compartments are built by lofting the divider walls up through the body, and the loft aligned its rings by the first vertex of each outline. Rotate an outline by a few degrees, which happens on a scooped cell, and the rings twist. One compartment in a 3x2 sorter came out sealed with a solid roof; the other five were fine, so the preview looked fine too. A stranger printed it, sent the report with the settings attached, and the fix was to align the rings relative to their centroid and cap the ends with fans from the same centre. It cost a spool of orange PETG worth of test bins to be sure, and the sorter in the previous Gridfinity post is one of them.

Next on the list is a lid: the standard has no official one, and my drawer of loose screws would like it to.