Button Spacing Calculator
Space any number of buttons evenly down a placket, measured from the top with an end offset you set.
On a fitted shirt, place one button at the fullest part of the bust first and space the rest from that point instead of splitting the placket evenly, so the front doesn't gape between buttons.
How it works
Give it the length of the placket (the strip where the buttons go), how many buttons you want, and how far the first and last button should sit from each end. The calculator puts the first button at that end offset, the last button the same distance from the bottom, and splits the remaining distance evenly between whatever buttons are left, rounded to the nearest hundredth of an inch so you can mark it with a ruler. With a single button it skips all that and just centers it on the placket.
Worked example: a 20 inch placket, 5 buttons, and a 2 inch end offset. The first button sits at 2 inches and the last at 18 inches, 2 inches up from the bottom. That leaves 16 inches between the first and last button, split across 4 gaps, for 4 inches of spacing between each one. The full list comes out to 2, 6, 10, 14, and 18 inches from the top. A shorter 10 inch placket with just 1 button and the same 2 inch offset simply centers that button at 5 inches, since a lone button doesn't need spacing math at all.
FAQ
Where should I put the first button on a fitted garment?
On a shirt or blouse with any shaping, place one button at the fullest part of the bust first, then measure and space the rest of the buttons out from that point rather than starting from the collar and working down. A gap that lands right at the fullest point of the body is the spacing mistake that actually shows.
What end offset should I use?
2 inches works well for most shirts and dresses, keeping the top button below the collar seam and the bottom button clear of a hem. A baby garment or a short cuff placket often wants a smaller offset, closer to 0.5 to 1 inch, so there's room for at least two buttons without crowding.
Which side do the buttonholes go on?
By long-standing convention, women's garments button left over right, so buttonholes go on the right side of the garment as worn, and men's garments button right over left, with buttonholes on the left. Follow whichever convention matches the pattern you're using if you want it to look standard.
Can I use this for a coat or a longer placket?
Yes, the math doesn't change with length. Just measure the full placket, decide how many buttons you want, and keep the end offset large enough that the top and bottom buttons aren't crowding the collar or hem.
For the stitching itself, see how to sew on a button by hand. If you're marking button positions from a commercial pattern instead of measuring your own placket, read how to read a sewing pattern for the first time, and check the beginner glossary if any of the terms here are new.