How to use this calculator
- Measure the drillable height. The interior face between the bottom and top panels (or rails) where holes may go.
- Set pitch and clearances. 32 mm pitch and ~64 mm minimum clearance at each end is typical; clearances also keep holes out of joinery and hinge plates.
- Pick centered or fixed-start. Centered splits the leftover equally (symmetric look); fixed-start indexes from the top clearance (jig-from-top workflows).
- Drill from one reference. Use the reported first-hole distance for every row, always from the same edge, with a depth stop.
How it works
Shelf-pin layout is integer arithmetic: how many holes of pitch
p fit in the drillable height after the end clearances, and
where does the run start so the leftover lands where you want it?
n = floor((H − c_t − c_b)/p) + 1, span = (n − 1)·p
The slack — what's left after the holes consume their span — either splits evenly (centered mode) or piles at the bottom (fixed-start mode). Both are correct; mixing them between rows is what produces rocking shelves. The 37 mm row setback keeps the layout compatible with system hardware: hinge base plates, drawer slides and shelf supports are all designed around it.
Around the same cabinet: the cabinet door size calculator and drawer box calculator size the fronts and boxes, and the shelf sag calculator answers whether the shelf spanning those pins will stay flat under the encyclopedia.
Worked example
Verified against the live calculator
A bookcase side with H = 700 mm of drillable height,
32 mm pitch and 64 mm minimum clearance each end:
n = floor((700 − 128)/32) + 1 = 18 holes, span = 544 mm
The 28 mm of slack splits to 14 mm a side in centered mode, so the first
hole lands 78 mm from the top and the last at
622 mm — leaving identical 78 mm margins top and bottom.
Drill the same schedule on all four rows (front and back of each side)
from the same top reference, 37 mm in from the edges, 9 mm deep.
Frequently asked questions
What is the standard shelf pin hole spacing?
32 mm center-to-center — the European cabinet system — with rows set back 37 mm from the front and back edges and 5 mm pins. The common imperial workflow uses 1/4 in pins on a 1-1/4 in (≈32 mm) pitch. Matching the standard keeps your holes compatible with jigs, hardware and drawer slides.
How far from the cabinet edge should shelf pin holes be?
37 mm from the front and back edges is the 32 mm system convention, and most commercial jigs index to it. Anything from 35-50 mm works structurally; what matters is that both rows on each side are identical and drilled from the same reference edge.
How deep should shelf pin holes be?
About 8-10 mm deep for 5 mm pins in 16-19 mm panels — deep enough for full pin engagement, shallow enough to leave a solid back wall. Use a depth stop; blowing through a finished side is the unrecoverable version of this mistake.
Why do my shelves rock on the pins?
Almost always a layout-reference error: one row drilled from the top while the mirror row was drilled from the bottom (or the jig flipped), so holes are offset by the leftover remainder. Drill every row from the same reference edge — the calculator reports the first-hole distance to make that explicit.
Method & assumptions
- Pure layout geometry — pin shear strength, shelf sag and panel material are separate questions (the shelf sag calculator covers the span side).
- Clearances are minimums: the centered mode adds the slack symmetrically on top of them.
- Hardware compatibility assumes the 32 mm system conventions (5 mm holes, 37 mm setback); decorative or antique-style supports may want custom spacing.