Fit & finishing / FREE CALCULATOR
Button spacing calculator
Lay out evenly spaced button centres between your chosen top and bottom offsets. Get every marking position from the top of the opening, so rounding does not build up along the placket.
Make your calculation
HOW IT WORKS
Measure the full opening and choose the two end offsets.
Enter the number of button centres, including the first and last.
Mark each result from the top edge, then check the garment on the wearer.
THE WORKING BEHIND THE NUMBER
A little more clarity.
THE METHOD
Interval = (opening length โ top offset โ bottom offset) รท (button count โ 1). Position n = top offset + (n โ 1) ร interval.
Mark from one reference edge
Measure every position from the top of the opening rather than repeatedly adding a rounded interval. This avoids a small rounding difference accumulating down a long placket. The offsets refer to button centres, not the edge of the button or the end of a buttonhole.
Choose the first and last locations for your actual garment before you calculate. Consider the neckline, hem, waistband seam and where the closure needs support. The tool spaces the intermediate centres equally between those chosen locations.
Check the layout before making buttonholes
A mathematical layout is only the beginning of placement. Try the garment on and inspect the chest and waist area in ordinary movement. You may choose an additional fastening or a deliberately unequal interval for a particular design.
Mark with a fabric-appropriate removable method and verify alignment with the opposite placket. The on-page diagram is a visual guide and must not be used as a full-size paper ruler. Print or copy the numeric marking list for the worktable.
A FEW USEFUL ANSWERS
Before you cut.
Why does the formula divide by one less than the button count?
There is one interval between each adjacent pair. Seven buttons therefore make six intervals.
Where should I measure the bottom offset?
Measure from the bottom of the opening to the centre of the last button. The calculator converts it into a position measured from the top.
Does equal spacing prevent gaping?
Not by itself. Fit, placket construction, fabric and the location of stress points also matter. Check placement on the worn garment before cutting buttonholes.