How to I Cord (Knitting)

I-cord (short for "idiot cord," the name Elizabeth Zimmermann gave it for how simple the mechanism is once understood) knits a narrow, seamless tube of fabric using a small number of stitches on double-pointed needles — no purling, no joining in the round in the usual sense, just repeated knitting from the same side of the work every row.

The trick that makes it work

Cast on a small number of stitches (commonly 3-5) onto a double-pointed needle. Instead of turning the work after knitting across, as ordinary flat knitting does, slide the stitches back to the other end of the same needle and knit across again from that same side — the working yarn pulls across the back of the work to reach the first stitch each time, and that pull is exactly what curls the fabric into a round, seamless tube rather than a flat strip.

The repeat

1. Knit all stitches across the needle.
2. Slide the stitches to the opposite tip of the same double-pointed needle (don't turn the work).
3. Pull the working yarn snug across the back to reach the first stitch, and knit across again.

Repeated indefinitely, this produces a continuously growing tube. The first several rows look messy and gappy before the tube "closes up" — this is normal and expected, not a sign of a mistake; the tube pulls itself closed as more rows accumulate tension.

Where it's used

As an edging, knit directly off live stitches along an edge (a cardigan front band, a blanket border) to create a rounded, cord-like trim rather than a flat ribbed or garter edge. As a drawstring or tie, worked as a separate standalone cord and attached afterward — hood ties, bag handles, the strings on a baby hat. As a bind-off ("i-cord bind-off"), worked at the very edge of a piece to finish it with a rounded cord edge instead of a standard bind-off, by knitting the cord stitches together with the live stitch being bound off at each row.

Where it goes wrong

The tube not closing up even after many rows. Usually means too many stitches were cast on relative to i-cord's typical count — a wider i-cord (6+ stitches) closes less readily than a narrower one (3-4 stitches), since there's proportionally more circumference for the working yarn's pull to close. If a wide i-cord genuinely won't close, working it on slightly smaller needles than the main project increases the pulling tension.

Visible gaps or a "seam" running down one side. Means the working yarn wasn't pulled snugly enough across the back between rows — deliberately tugging the yarn firm (more than feels necessary) before knitting the first stitch of each new row closes this gap over time as the cord grows.

I-cord edging pulling the main fabric's edge in or out of shape. If the cord itself is worked tighter or looser than the piece it's finishing, it can pucker (too tight) or ripple (too loose) the edge — working a swatch of the edging technique on a scrap piece first helps catch a tension mismatch before committing to a full garment edge.

I-cord bind-off specifically

Unlike a plain i-cord worked separately, i-cord bind-off is worked directly along a piece's live edge: cast on a few extra stitches at the start of the row (commonly 3), then at each step, knit those extra stitches together with the next live stitch from the main piece, effectively binding off one main stitch per i-cord row while growing the cord along the edge. This produces a rounded, finished edge in one pass rather than working the cord separately and sewing it on afterward.

A quick way to make cord for other purposes

Because i-cord is fast to produce and needs minimal setup (a couple of double-pointed needles and a small stitch count), it's a common go-to for anything needing a knit cord — not just garment ties, but stuffed-toy limbs, bag straps, or decorative trim — independent of whatever main project it's paired with.

Attaching a separately worked i-cord

An i-cord knit as its own standalone piece — a hood tie, a bag strap — usually needs to be sewn on afterward rather than knit directly out of the main fabric. Whip-stitching along the cord's flat underside with a matching-color strand, catching a small amount of the main fabric with each stitch, keeps the attachment nearly invisible from the right side; sewing through the cord's rounded top surface instead tends to flatten and distort its shape.

FAQ

Does i-cord require double-pointed needles specifically, or can other needles work? Double-pointed needles are the traditional tool since the technique relies on sliding stitches to the opposite tip of the same needle, which a straight or standard circular needle can't do the same way; a short circular used carefully can sometimes substitute, but double-points remain the standard tool.

How many stitches should an i-cord use for a typical drawstring or tie? 3-4 stitches is the most common range for a narrow tie or drawstring; wider i-cord (5+ stitches) is used when a thicker cord is wanted, though it takes more rows to fully close and reads more like a narrow tube than a tight cord at that width.

Can i-cord be worked in a color pattern, like stripes? Yes — because it's knit continuously from the same side, changing colors between rows produces clean horizontal stripes around the cord, a straightforward way to add a decorative pattern to an otherwise plain cord.