Work out button quantity instantly with clear inputs, formula shown and shareable results.
Buttons sit at both ends of the placket, so the count is the number of gaps plus one, and the actual spacing is the placket length divided by that gap count. The gaps-plus-one rule is why six buttons at 8 cm nominal spacing on a 60 cm placket actually sit 8.57 cm apart once evened out.
Button count
buttons = round(placket length / target spacing) + 1
Even spacing
spacing = placket length / (buttons - 1)
buttons = round(placket length / target spacing) + 1. Buttons sit at both ends of the placket, so the count is the number of gaps plus one, and the actual spacing is the placket length divided by that gap count.
The gaps-plus-one rule is why six buttons at 8 cm nominal spacing on a 60 cm placket actually sit 8.57 cm apart once evened out.
Enter length of the button placket, target spacing between buttons, spare buttons to buy. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.