Reference Chart
Crochet Hook Size Chart
Metric millimetre, US letter/number, and UK sizes for every standard crochet hook — plus a separate table for steel thread hooks and recommended ranges for each yarn weight class. Type any size in the search box to highlight it across both tables.
Standard crochet hooks
Aluminium, plastic, ergonomic, and tunisian hooks — all measured by shaft diameter in millimetres.
| Metric (mm) | US size | UK / Canada |
|---|---|---|
| 2.0 mm | — | 14 |
| 2.25 mm | B-1 | 13 |
| 2.5 mm | — | 12 |
| 2.75 mm | C-2 | — |
| 3.0 mm | — | 11 |
| 3.25 mm | D-3 | 10 |
| 3.5 mm | E-4 | 9 |
| 3.75 mm | F-5 | — |
| 4.0 mm | G-6 | 8 |
| 4.25 mm | G | — |
| 4.5 mm | 7 | 7 |
| 5.0 mm | H-8 | 6 |
| 5.5 mm | I-9 | 5 |
| 6.0 mm | J-10 | 4 |
| 6.5 mm | K-10½ | 3 |
| 7.0 mm | — | 2 |
| 8.0 mm | L-11 | 0 |
| 9.0 mm | M/N-13 | 00 |
| 10.0 mm | N/P-15 | 000 |
| 11.5 mm | P-16 | — |
| 15.0 mm | P/Q | — |
| 16.0 mm | Q | — |
| 19.0 mm | S | — |
| 25.0 mm | T/U/X | — |
— means no standard size designation exists at that millimetre measurement.
Steel (thread) crochet hooks
Steel hooks use a separate, inverted scale — a higher number means a smaller hook. They overlap standard hooks in millimetres but never in labelling, which is why a “size 2” steel hook (2.25 mm) and a “size 2” standard hook are nothing alike. Use these for fine thread crochet, lace, doilies, and beadwork.
| US steel size | Metric (mm) |
|---|---|
| 00 | 3.5 mm |
| 0 | 3.25 mm |
| 1 | 2.75 mm |
| 2 | 2.25 mm |
| 3 | 2.1 mm |
| 4 | 2.0 mm |
| 5 | 1.9 mm |
| 6 | 1.8 mm |
| 7 | 1.65 mm |
| 8 | 1.5 mm |
| 9 | 1.4 mm |
| 10 | 1.3 mm |
| 11 | 1.1 mm |
| 12 | 1.0 mm |
| 13 | 0.85 mm |
| 14 | 0.75 mm |
US letter sizes are not standardised between manufacturers
The metric measurement is the only reliable one. Letter sizes vary between brands — a hook stamped “G” is 4.0 mm from some manufacturers and 4.25 mm from others, and both are sold as G. You can see this reflected in the table above, where both 4.0 mm and 4.25 mm appear under different G designations.
If a pattern specifies a letter and your gauge is off, check the millimetre marking stamped on the shaft before assuming your tension is the problem. When buying hooks from a brand you haven’t used before, verify the mm size on the package.
UK and Canadian sizes run inverse to metric: the number gets smaller as the hook gets larger. UK 14 is 2.0 mm; UK 000 is 10 mm. Many modern patterns from UK designers now specify metric instead of the old number system.
Which hook for which yarn weight
Starting points, not rules. Your gauge swatch decides the final hook — these ranges are where patterns typically assume you’ll begin. Yarn weight categories follow the Craft Yarn Council standard.
| Yarn weight | Hook range | US equivalent |
|---|---|---|
| 0 — Lace | 1.4–2.25 mm | steel 8 to B-1 |
| 1 — Super Fine | 2.25–3.5 mm | B-1 to E-4 |
| 2 — Fine | 3.5–4.5 mm | E-4 to 7 |
| 3 — Light | 4.5–5.5 mm | 7 to I-9 |
| 4 — Medium | 5.5–6.5 mm | I-9 to K-10½ |
| 5 — Bulky | 6.5–9 mm | K-10½ to M/N-13 |
| 6 — Super Bulky | 9–15 mm | M/N-13 to P/Q |
| 7 — Jumbo | 15 mm and up | P/Q and larger |
Crochet hook size FAQ
What size crochet hook do I need for worsted weight yarn?▼
For worsted weight (size 4 — Medium), the standard starting range is 5.5 mm to 6.5 mm (US I-9 to K-10½). Most patterns call for a 5.5 mm or 6.0 mm hook. Always check your pattern's gauge swatch — hook size affects stitch tension more than yarn weight alone.
What is the difference between US and metric crochet hook sizes?▼
The metric measurement in millimetres is the diameter of the hook shaft and is the only standardised measurement. US letter and number sizes are informal labels that vary between manufacturers — a "G" hook can be 4.0 mm from one brand and 4.25 mm from another. Always match by the mm marking stamped on the shaft, not the letter.
What are steel crochet hooks used for?▼
Steel hooks are used for thread crochet: lace, doilies, and beadwork using fine cotton thread. They use a separate, inverted numbering system where higher numbers mean smaller hooks — a steel size 14 (0.75 mm) is the smallest; a steel size 00 (3.5 mm) is the largest. A "size 2" steel hook is 2.25 mm, completely different from a "size 2" standard hook.
What does the UK crochet hook numbering system mean?▼
UK sizes run inversely to metric: the number decreases as the hook gets larger. UK 14 is 2.0 mm; UK 000 is 10.0 mm. Many modern UK and Canadian patterns now specify metric millimetres instead, so the old number system mainly comes up when working from older patterns published before metric became standard.
Why does my gauge not match the pattern even with the right hook?▼
Gauge depends on your personal tension, not just hook size. If your swatch is too tight (too many stitches per inch), go up one hook size. If it's too loose, go down one size. Yarn fibre content and your individual crochet style both affect gauge. Always swatch before starting a sized garment.
Browse all charts
Reference Charts
Size conversion tables, grit charts, and drill bit guides for every craft.
Calculator
Quilt Backing Calculator
Exact backing yardage with seam layout and binding strips.