Buttonhole Spacing Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 28, 2026Buttonhole Spacing Calculator
Get perfectly even buttonhole spacing marked out before you sew a single one - this calculator does the math for you.
Usable Length = Placket Length - (Top/Bottom Margin x 2)
Spacing = Usable Length / (Number of Buttonholes - 1)
Example
A 24-inch placket, 7 buttonholes, 0.5-inch top/bottom margin:
Usable Length = 23.00 in → 3.83 inches between buttonhole centers
Why the Division Uses "Buttonholes Minus 1"
With buttonholes placed at both ends of the usable length as well as evenly between, there are always one fewer gaps than there are buttonholes - dividing by (buttonholes - 1) correctly accounts for this, rather than dividing by the raw buttonhole count.
Mark Before You Sew
Marking all buttonhole positions along the entire placket before sewing any of them - rather than sewing one and eyeballing the position of the next - ensures perfectly even spacing across the full length, avoiding a visibly uneven, amateur-looking result.