P/Q crochet hook: P/Q is 15 mm

A US size P/Q crochet hook is 15 mm at most brands. Turned around: a hook stamped 15 mm is usually sold as a P/Q.

The letter and the number are one hook, not two — “P/Q” is a single size. Older hooks often print only one of the pair, which is most of the confusion. The millimeter is stamped on the hook itself, so when a pattern and a label disagree, trust the mm.

What yarn this hook is for

15 mm falls in the hook range the Craft Yarn Council suggests for 2 yarn weights — guidelines, in their own words, not rules:

• Super Bulky (6) — also sold as Super Bulky, Roving. Expect about 7–9 single crochet to 4 inches.
• Jumbo (7) — also sold as Jumbo, Roving. Expect 6 single crochet or fewer to 4 inches.

Before you trust the letter

The Craft Yarn Council puts it plainly: “Because letter and number sizing vary from company to company, rely on the package millimeter (mm) sizing, which is an accurate measurement.” Only E (3.5 mm) and H (5 mm) mean the same thing at every brand — a hook stamped G is 4 mm from Susan Bates or Clover and 4.25 mm from Boye, and from L upward the letters drift far enough that the Council stops printing single ones.

The sizes either side

• One size down: O — 12 mm
• One size up: Q — 15.75 mm

Half a millimeter is enough to change how a finished piece comes out. If your gauge is off, this is the dial to turn before you change anything in the pattern — the gauge calculator says which way to go.

See every hook size in one chart →