Buttonhole Spacing Calculator
Even button placement down a placket.
Calculate evenly spaced button positions down a placket from the first and last positions and the number of buttons.
Measured down from the neckline.
Spacing between buttons
4.00"
6 buttons over 20.00"
Six buttons have five gaps, not six — dividing by the button count instead is why a set of buttonholes ends up short of the intended last position. Place one button at the fullest point of the bust regardless of the even spacing: that is where a placket gapes, and nothing else fixes it.
How the Buttonhole Spacing Calculator works
Button spacing is a division, and the interesting part is what fixes the ends. The first and last positions are design decisions — one of them almost always at the fullest point of the bust, because that is where a placket gapes — and everything between divides the remaining distance evenly.
Also known as: button placement calculator · button spacing calculator
Gaps, not buttons
Even spacing divides the distance between the first and last buttons by the number of gaps, and there is always one fewer gap than there are buttons. Six buttons have five gaps.
Dividing by the button count instead is why a set of buttonholes comes out short of the intended last position — the error is one gap's worth, which on a shirt front is three or four inches.
The first and last positions are design decisions rather than outputs. One of them should sit at the fullest point of the bust, because that is where a front placket pulls open and where even spacing elsewhere does not help.
A worked example
Six buttons from 2 inches below the neckline to 22 inches: a 20 inch span over five gaps, so 4 inch spacing, with buttons at 2, 6, 10, 14, 18 and 22.
Divide by six instead and the spacing is 3.33, putting the last button at 18.67 — over three inches short of where the placket needed it to end.
Where the answer misleads
Perfectly even spacing is not always right. If the bust point falls between two evenly spaced buttons, the placket will gape there regardless, and the correct answer is to place one button at the bust point and space the others around it — accepting slightly uneven gaps for a garment that stays closed.
Button size affects perceived spacing. Large buttons at a spacing that looks generous on small ones can look crowded, so the number of buttons is worth revisiting when the button changes.
Finally, horizontal buttonholes on a placket sit slightly off-centre — the button pulls to the end of the hole nearest the edge — so the buttonhole starts about an eighth of an inch beyond the centre line rather than on it.
Frequently asked questions
How do I space buttons evenly?
Fix the first and last positions, then divide the distance between them by one less than the number of buttons. Six buttons from 2 to 22 inches gives a 4 inch spacing, because there are five gaps rather than six.
Where should the first button go?
Design decides the top one, but one button should sit at the fullest point of the bust. That is where a front placket pulls open, and no amount of even spacing elsewhere fixes a gap there.
How far apart should shirt buttons be?
Three to four inches on a shirt, closer on a fitted blouse where gaping is more likely, and further on a coat with large buttons. Larger buttons generally want more space so they do not look crowded.
Why one less gap than buttons?
Because the gaps are between buttons. Six buttons have five spaces between them, and dividing by six instead is the reason a set of buttonholes ends up short of the intended last position.