Buttonhole Spacing Calculator
Calculate even spacing between buttonholes along a placket length.
Reviewed by the ToolNestr Editorial Team — July 2026
How buttonhole spacing is calculated
This calculator first subtracts the top and bottom margins from the total placket length, leaving the usable length where buttons actually sit. Because the first and last button are placed at the edges of that usable length, the number of gaps between buttons is always one less than the number of buttons — dividing the usable length by (button count minus 1) gives the even spacing between each buttonhole's center.
This even-spacing approach works well for most plackets, though many sewists adjust it slightly in practice to place one button at a specific stress point (like the fullest part of the bust on a fitted shirt) and then space the rest evenly around that anchor point instead of purely top to bottom.
This follows the standard evenly-divided spacing method used across shirt and garment placket construction.
Worked example
A 26-inch shirt placket, 7 buttons, 0.75-inch margins top and bottom.
Real-world context
Shirt-making is the classic use case, since a shirt placket needs visibly even spacing to look professionally finished — uneven buttonhole spacing is one of the most noticeable signs of a home-sewn garment compared to a ready-to-wear one, making this a small calculation with an outsized effect on perceived quality.
Duvet covers, pillowcases with a button closure, and other home-decor items with multiple buttons benefit from the same even-spacing math, though the margins and typical spacing distances involved are usually larger than on a fitted garment placket.
Common misconceptions
"Spacing equals placket length divided by button count." Off by one. The correct divisor is one less than the button count, since the first and last buttons sit at the very edges of the usable length rather than the spacing repeating past the last button.
"Even mathematical spacing always looks best regardless of the garment." Not always. Fitted garments often benefit from anchoring a button at a specific stress point rather than pure even spacing, since a perfectly even mathematical spread can place a gap at an awkward point like the bust or a seam intersection.
Related tools
Frequently asked questions
What margin should I use at the top and bottom?
A common top margin on a shirt placket is about 0.5-0.75 inch from the neckline edge; the bottom margin (or the space before the last button) depends on the garment length, but should be enough to prevent the buttonhole from being too close to the hem or an existing seam.
Does this work for a button placed at a stress point, like a collar or bust?
This calculator gives even spacing across the whole placket; in practice, sewists often anchor one buttonhole exactly at a stress point (like the fullest part of the bust) first, then space the remaining buttons evenly around that fixed point rather than purely evenly top to bottom.
How many buttons should a shirt have?
This varies by style and placket length, but a common range for an adult shirt is 6-8 buttons; use your placket length and desired spacing (roughly 3-4 inches apart) to estimate a reasonable button count if you're designing from scratch.
Does spacing include the buttonhole's own length?
This calculator gives the spacing between the centers of each buttonhole; make sure adjacent buttonholes have enough room between their centers to fit the buttonhole length itself without overlapping.