Yarn & Needlecraft
What Size Crochet Hook Do I Have?
Compare the straight shaft of the hook, not the hook head. Metric millimeters are the physical source of truth.
Confirm calibration
Calibrate your display for best accuracy before comparing objects.
Compare shaft diameters
Compare the straight shaft of the hook, not the hook head. Tap the circle that matches.
Compare two hook shafts— side-by-side or overlay
Difference highlight uses calibrated --px-per-mm. Solid = A, dashed = B in overlay.
Can't find what you're measuring?
Crochet Hook Size Chart
Use this crochet hook size chart after comparing on screen. US letter and number aliases are shown only where conversion charts agree. Trust the millimeter marking when hooks are stamped. Steel and thread hooks use a separate scale and are not included.
| Metric (mm) | US reference | Typical yarn |
|---|---|---|
| 2.25 mm | B-1 | Lace / fingering |
| 2.75 mm | C-2 | Fingering |
| 3.25 mm | D-3 | Sport |
| 3.5 mm | E-4 | Sport / DK |
| 3.75 mm | F-5 | DK |
| 4 mm | G-6 | DK / worsted |
| 4.5 mm | 7 | Worsted |
| 5 mm | H-8 | Worsted |
| 5.5 mm | I-9 | Worsted / bulky |
| 6 mm | J-10 | Bulky |
| 6.5 mm | K-10.5 | Bulky |
| 8 mm | L-11 | Super bulky |
| 9 mm | M-13 | Super bulky |
| 10 mm | N-15 | Jumbo |
| 15 mm | P/Q | Jumbo |
Closest standard size. Calibrate your display for best accuracy. Verify critical measurements using appropriate physical measuring equipment. Steel/thread hooks use a separate scale and are not included here.
Common questions
How do I find my crochet hook size if it is unmarked?
Calibrate your screen, then compare the straight shaft—not the bent hook head—to actual-size metric circles. Millimeters are the physical source of truth. The chart below lists US letter aliases only where conversion charts agree.
What size is an H crochet hook in mm?
In this chart, US H-8 maps to 5.0 mm shaft diameter. Always prefer a stamped millimeter marking when present—letter labels can vary slightly by maker.
Should I measure the hook head or the shaft?
Measure the straight shaft diameter. The bent hook head is not the sizing reference and will give a false reading.
Why do US letter sizes sometimes disagree between brands?
Letter and number aliases are conversion labels, not physical standards. This page shows US aliases only where industry charts agree. When a hook is stamped in millimeters, trust that marking over the letter.
Are steel and thread crochet hooks included?
No. Steel and thread hooks use a separate numbering scale and are excluded from this chart. Yarn hooks sized in millimeters (with optional US aliases) are covered.
How do I tell two close hook sizes apart?
Open Compare two hook shafts on this page and place both candidate diameters side by side at calibrated size. Small differences (for example 5.0 mm vs 5.5 mm) are easier to see that way than guessing from memory.