Button Spacing Calculator
Calculate even button spacing for any number of buttons over a garment length.
Returns exact position of each button from top and bottom in inches and cm.
The math is simple — the placement decisions are not
Even button spacing is straightforward arithmetic: distance between buttons equals usable length divided by gaps, where gaps = (button count − 1). For a 55 cm placket with a 2.5 cm margin top and bottom and 6 buttons, you get 50 cm of usable length divided into 5 gaps, or exactly 10 cm between buttons.
But evenly spaced buttons are not always the right answer. Garment construction has rules about where each button must land regardless of math.
Anchor points that decide button placement
A shirt or blouse needs a button at three specific locations before you space anything evenly:
- Bust apex — the fullest point of the chest. A button here prevents the placket gaping open (“the bust gap”). On a women’s shirt, fitting a button at the apex is non-negotiable.
- Waist — at the natural waist if the garment is fitted, prevents pull at the front waist.
- Top button — about 1 cm below the collar attachment, hidden under the collar stand when buttoned.
Space the remaining buttons evenly between those fixed points, not against the total garment length. A common beginner mistake is to math out perfectly even spacing on a finished pattern, only to end up with no button at the bust apex and a permanent gap there.
Number of buttons by garment
| Garment | Typical button count | Spacing (approx) |
|---|---|---|
| Men’s dress shirt | 7 to 9 | 8 to 10 cm |
| Men’s casual shirt | 6 to 7 | 9 to 12 cm |
| Women’s blouse | 5 to 8 | 7 to 10 cm |
| Cardigan | 5 to 9 | 6 to 9 cm |
| Tailored blazer | 1, 2, or 3 | n/a (specific anchor points) |
| Coat | 3 to 5 | 12 to 18 cm |
| Cuff | 1 to 3 | 1.5 to 2.5 cm |
Buttonhole orientation rule
Horizontal buttonholes on plackets, vertical buttonholes on shirt fronts (or anywhere the placket is narrow). Horizontal holes let the button shift sideways under tension without unbuttoning, which is why coats and waistband closures use them. Vertical holes lie flatter and look cleaner on a thin placket where the button has nowhere to drift.
The buttonhole length is the button diameter plus its thickness, never just the diameter. A 1.5 cm button with a flat 2 mm shank needs a 1.7 cm buttonhole. Cut on the short side, then test, then extend if needed.
Marking the placement on the actual fabric
Mark from the finished neckline down, not from the cut edge. Cut edges get hemmed, gathered, or trimmed, so they are not a stable reference. Use tailor’s chalk or a removable fabric marker, and pin-mark before cutting any buttonhole — once cut, you cannot move the hole if you measured wrong.