Buttonhole Spacing Calculator
On a 60 cm placket with 2 cm clear at each end, the buttonholes occupy 56 cm. Six buttons divide that by five, not by six: the first and last sit at the ends of the span, so there are only five gaps between them. That is 56 ÷ 5 = 11.2 cm. Divide by six instead and you get 9.3 cm, leaving the last hole stranded well short of the end.
Your numbers
Spacing between buttonholes
11.2cm
Span the buttonholes cover
56cm
Formula
Spacing between buttonholes = (Placket length − 2 × Margin at each end) ÷ (Buttons − 1)
On a blouse, place one buttonhole at the fullest part of the bust first and space the others from there — even spacing alone leaves that point between two holes, which is exactly where the front gapes. The hole itself still has to be as long as the button diameter plus its thickness.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Placket length (cm)The whole length of the button band, neckline to hem. | 60 | 1 and up |
| ButtonsHow many buttons go on — the same as the number of holes. | 6 | 2 and up |
| Margin at each end (cm)The clear length left at each end of the band, top and bottom alike. | 2 | 0 and up |
Step by step
Quick reference table
Results when only Placket length (cm) changes and everything else stays put.
| Placket length (cm) | Spacing between buttonholes (cm) | Span the buttonholes cover (cm) |
|---|---|---|
| 30 | 5.2 | 26 |
| 45 | 8.2 | 41 |
| 60 | 11.2 | 56 |
| 90 | 17.2 | 86 |
| 120 | 23.2 | 116 |
What each result means
| Result | At default values |
|---|---|
| Spacing between buttonholes (cm)Centre to centre between holes; there is one fewer gap than there are buttons. | 11.2 |
| Span the buttonholes cover (cm)First hole to last hole — the band less both end margins. | 56 |
Common mistakes
On a blouse, place one buttonhole at the fullest part of the bust first and space the others from there — even spacing alone leaves that point between two holes, which is exactly where the front gapes. The hole itself still has to be as long as the button diameter plus its thickness.
Glossary
- Placket length
- The whole length of the button band, neckline to hem.
- Buttons
- How many buttons go on — the same as the number of holes.
- Margin at each end
- The clear length left at each end of the band, top and bottom alike.
- Spacing between buttonholes
- Centre to centre between holes; there is one fewer gap than there are buttons.
- Span the buttonholes cover
- First hole to last hole — the band less both end margins.
Frequently asked questions
Q. How is Buttonhole Spacing Calculator calculated?
Spacing between buttonholes = (Placket length − 2 × Margin at each end) ÷ (Buttons − 1) — On a 60 cm placket with 2 cm clear at each end, the buttonholes occupy 56 cm. Six buttons divide that by five, not by six: the first and last sit at the ends of the span, so there are only five gaps between them. That is 56 ÷ 5 = 11.2 cm. Divide by six instead and you get 9.3 cm, leaving the last hole stranded well short of the end.
Q. Can you walk through an example?
With Placket length 60cm, Buttons 6, Margin at each end 2cm, the answer is Spacing between buttonholes 11.2cm.
Q. What do I need to enter?
Enter Placket length, Buttons, Margin at each end. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Placket length (cm) moves the answer to Placket length (cm) 30 → Spacing between buttonholes (cm) 5.2 and Placket length (cm) 120 → Spacing between buttonholes (cm) 23.2. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
On a blouse, place one buttonhole at the fullest part of the bust first and space the others from there — even spacing alone leaves that point between two holes, which is exactly where the front gapes. The hole itself still has to be as long as the button diameter plus its thickness.
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