Buttonhole Stitch

Intermediate Finishing

A dense, looped stitch worked edge to edge with no gaps, used to reinforce buttonholes and other edges that need to withstand repeated stress.

Bring the needle up from the back, close to the edge you're reinforcing.
Insert the needle down through the fabric a short distance from the edge, directly out from where the thread emerged, and bring the tip back up right at the edge.
Before pulling the needle through, catch the working thread under the tip so it loops around as you pull — this locks the stitch against the edge.
Pull the thread snug so the looped knot sits directly on the edge, then move over and repeat immediately next to the last stitch, with no gap between them.
Continue packing the stitches tightly along the whole edge for a solid, reinforced border.

The technique is identical to blanket stitch — the only difference is spacing: buttonhole stitch packs the stitches edge to edge with no gap, while blanket stitch leaves visible space between them.
Working the stitches densely is what lets buttonhole stitch withstand the repeated friction of a button sliding through, without the edge fraying.
For a rounded buttonhole end, fan the stitches slightly around the curve instead of keeping them perfectly parallel.