Why does my crochet curl at the edges or ripple?

Stitch count drift, tension against hook size, and the difference between a curling flat piece and a rippling circle.

Difficulty: beginner
Time: 20 min
Read: 3 min

Short answer

A flat piece that curls usually means the tension is too tight for the hook — go up a hook size. A circle that ripples means you are adding too many stitches per round; a circle that cups means too few.

Crochet fabric is stiffer than knitting, so tension and stitch-count errors show up as physical distortion rather than as a slightly odd size. That makes the shape of the problem a good diagnostic.

Step by step

Work out which problem you have.A flat rectangle curling at the edges is a tension problem. A circle that ruffles or cups is a stitch-count problem. A rectangle that narrows or widens is a count problem too.
Go up a hook size for a curling flat piece.Curling in a flat piece almost always means the stitches are too dense for the yarn. Increasing the hook size is far more effective than trying to relax.
Count stitches at the end of every row or round.It is tedious and it is the only reliable way to catch a drift of one stitch that will otherwise take twenty rows to become visible.
Get the increases right in a flat circle.A flat circle in double crochet needs the same number of increases each round — six in round one, then six more spread evenly each round. Fewer and it cups into a bowl; more and it ruffles.
Spread increases evenly.Stacking increases directly above each other produces corners and a hexagon rather than a circle. Offset them each round.
Check the turning chain rule.Decide whether the turning chain counts as a stitch for your pattern and stick to it. Inconsistency adds or removes a stitch at one end of every row.
Block the finished piece.Wet or steam blocking relaxes the stitches and pins the piece into shape. Natural fibres hold blocking well; acrylic needs steam and holds it permanently once done.
Accept that some stitches curl naturally.Rows of plain double crochet curl more than taller stitches. A border of a different stitch round the edge settles it.

Tips

Curling flat piece: bigger hook. Rippling circle: fewer increases. Cupping circle: more increases.
Count every row. A one-stitch drift is invisible until it is twenty rows deep.
Steam blocking makes acrylic hold its shape permanently — wet blocking does not.

Common mistakes

Trying to crochet more loosely rather than changing hook — Deliberately altered tension is not sustainable across a whole project, so the fabric changes partway through. Changing the hook changes the stitch size reliably.
Stacking increases in the same place each round — The extra stitches all fall on the same radius, so the circle grows corners and turns into a polygon rather than staying round.

If it doesn't work

Flat piece curls at the edges

Cause: Tension too tight for the hook — Fix: Go up a hook size, and add a border row in a taller stitch.

Circle ruffles at the edge

Cause: Too many increases per round — Fix: Reduce to the correct fixed number of increases per round and undo the ruffled rounds.

Circle cups into a bowl

Cause: Too few increases per round — Fix: Add the correct number of evenly spread increases per round.

Rectangle narrowing

Cause: Missing the last stitch of rows — Fix: Count each row and work into the final stitch.

Questions people ask

Will blocking fix a curling piece?

It helps considerably with natural fibres and, with steam, permanently with acrylic. It will not fix a stitch-count error — a rippling circle stays rippled.

How many increases does a flat circle need?

For double crochet, six per round: six stitches in round one, twelve in round two, eighteen in round three and so on. Taller stitches need a different fixed number.