Knit button loops are a perfect alternative to buttonholes when you do not need a tight closure. Button loops are ideal to secure a flap closure, such as with a purse, or if you want to secure a fit, such as buttoning a hat to make it fit tighter. In fact, button loops can even be made as an afterthought and sewn on your knit project wherever you want. For example, you could add a button loop (and button) to an oversized sweater to draw in the waist, to an open tote bag you would like to secure closed, to close an open cardigan or to a shawl to keep it snug around your shoulders.
Cast three stitches on your knitting needle.
Knit the three stitches. Do not turn your work.
Slide the stitches to the other end of the needle.
Repeat Steps 2 and 3 until the cord produced (called "i-cord") is the desired length. The right length for your project will depend on the size of the button; the button should be just able to pass through the loop.
Sew the loop in place and weave in the ends. You could have the cord ends together or lay the loop flat against an edge.
Mark the button placement before attaching your button loop. Buy your buttons before making your button loop so that you can make the perfect size loop. Instead of making an i-cord for your button loop, you could finger-knit or crochet a chain. They work the same! A button loop for a flat button must be smaller than a button loop for a raised button. Twist your cord before stitching it on the garment to give it a different look. Use a matching thread to sew the button loops on or use the same yarn you used to make the cord.
Your button loops will stretch a little during use, so make sure it is tight to start with.