Button Spacing Calculator
Calculate even spacing for buttons along a garment placket, given the placket length, the margin from each end, and how many buttons you want.
How the spacing is worked out
The first and last buttons sit on the margins and the rest divide the run between them, so the number of gaps is one fewer than the button count:
usable = placket length - (2 × end margin)
spacing = usable / (buttons - 1)
button i = margin + (i - 1) × spacingWith the defaults - a 24 in placket, 1 in margins, 6 buttons - the usable run is 22 in and the spacing is 22 / 5 = 4.4 in. Buttons land at 1, 5.4, 9.8, 14.2, 18.6 and 23 inches from the top. Dividing by 6 instead of 5 is the classic error: it returns 3.667 in and leaves the last button 4.4 in short of the hem.
Setting the margins and the count
- Measure the finished band - neckline edge to hem, after the collar or facing is on, not the whole garment front.
- Put a button where the garment pulls. On a cardigan that is the fullest point of the bust: choose the margin so a button falls there and let the spacing fill in around it.
- Buttonholes are cut from the mark, not on it. A horizontal buttonhole starts about 1/8 in past the centre line so the shank settles back onto it; a vertical one is centred on the figure shown.
Frequently asked questions
How far apart should buttons be on a cardigan?
Roughly 3 to 4 in centre to centre for an adult, 2 to 3 in for a child. A 22 in usable run takes six or seven buttons; fewer and the fronts gape.
Why is the spacing divided by one less than the button count?
Both end buttons are fixed on the margins. Six buttons make five gaps, so a 22 in run divides into five lengths of 4.4 in, not six of 3.667 in.
Can I set the end margin to zero?
Yes, and the first button then sits on the very edge of the placket. It is rarely wanted, because a button needs its own radius of band to sit flat.