BO — Bind off (Abbreviation)
BO stands for "bind off" (called "cast off" in UK patterns — same technique, different regional term) — the instruction that closes off live stitches so they can't unravel, typically at the very end of a piece or wherever a section of fabric needs to be permanently finished mid-pattern.
The basic mechanic
Knit two stitches, then lift the first stitch worked over the second and off the needle, leaving one stitch remaining; knit one more stitch, and repeat the lift-over across the whole row. The last remaining loop is cut and pulled through to secure it. This standard method is what most patterns mean by a bare "BO" with no further qualifier.
Why bind-off tightness matters more than most knitters expect
A standard bind-off worked at ordinary tension comes out noticeably less stretchy than the fabric below it — for an edge with no need to stretch, this is fine, but for a ribbed edge that's supposed to stretch (a sock cuff, a sweater hem), a too-tight standard bind-off can undo all the elasticity the rib itself provides. Many patterns specifically call for a stretchier bind-off method at exactly these edges for this reason.
Where it shows up
Almost always at a piece's very end, but also mid-pattern for a section that's finished early — a sleeve's underarm stitches bound off before continuing the body, for instance.
Related abbreviations
- CO — cast on, the opening counterpart most patterns pair with BO at the end
- k2tog — a right-leaning decrease, mechanically similar in principle to the lift-over motion bind-off uses
FAQ
Is bind off the same action as three-needle bind-off? Related but distinct — three-needle bind-off joins two separate pieces' live stitches while binding off, whereas a standard BO closes a single piece's stitches with no second piece involved.
Should I always use a stretchier bind-off for a ribbed edge? Not automatically required, but worth considering — if a finished ribbed edge feels tighter than the rest of the piece once bound off, a stretchier bind-off method (worked out over larger needles, or a dedicated stretchy technique) on the next similar project addresses it directly.