Crochet Hook and Yarn Weight Calculator

Smallest hook ~ Largest hook ← Yarn weight number (0 ~ 7) — The numbers run from 0 (lace) to 7 (jumbo). Weight 4 — worsted or aran — takes a 5.5–6.5 mm hook at roughly 11–14 single crochet per 10 cm, so the middle of the band is 6.0 mm and 12.5 stitches. Weight 3 (DK) is 4.5–5.5 mm at 12–17, weight 5 (chunky) is 6.5–9 mm at 8–11. Amigurumi deliberately drops 1–1.5 sizes below this to make fabric dense enough to hide the stuffing.

With Yarn weight number 4, the answer is Hook size 6mm.

Enter Yarn weight number. The result recalculates as you type, and an empty box counts as zero.

Changing only Yarn weight number moves the answer to Yarn weight number 2 → Hook size (mm) 4 and Yarn weight number 7 → Hook size (mm) 20. The table below lays out five steps.

Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.

This mapping is a convention, not physics. The weight number is a category set by companies and national bodies rather than a measured range, so two yarns both labelled 4 can run 180 m and 230 m per 100 g. The gauge on a yarn band is usually a knitting figure as well, and crochet uses a larger hook with larger stitches on the same yarn. Treat the size here as the hook you swatch with first. Where a pattern states its own gauge, that beats this table.