Hook sizes are a starting point. A pattern says “4 mm” or “G-6”, the yarn label suggests a range, and then your hands decide the actual gauge. Two crocheters using the same hook and yarn can produce different fabric, which is why a swatch is still the final answer.

The millimetre size is the reliable number. Letter and number sizes vary between manufacturers, and a “G” from one brand can be a different millimetre size from another.

Read the size on the hook

Use the millimetre marking, not the letter or number, when comparing hooks. The CYC advises relying on the metric size printed on the package because letter sizing is not standardised. If the marking has worn off, measure the shaft with calipers.

Steel hooks use a separate, reverse scale; a steel 7 is 1.4 mm, not 7 mm. See the steel hook chart if the pattern specifies a steel size.

Match the gauge

  1. Crochet a swatch at least 15 cm square in the pattern's stitch.
  2. Measure stitches and rows over 10 cm after washing and drying.
  3. Too many stitches per 10 cm: the fabric is too tight; go up a hook size.
  4. Too few stitches: the fabric is too loose; go down a hook size.
  5. Re-swatch after each change. A 0.5 mm change can move the gauge by a stitch or more.

A worked example

The pattern asks for 16 single crochet stitches per 10 cm. Your swatch gives 18. On a 100 cm-wide project, the pattern would use 160 stitches; at your gauge, 160 stitches would measure about 89 cm.

Go up one hook size and re-swatch. If the gauge moves to 16, the pattern's stitch count works. If it moves to 17, you can either adjust the stitch count or accept a slightly denser fabric, depending on the project.

Tension, not just the hook

Gauge is the combination of hook, yarn, stitch and hand tension. A few practical points:

  • Be consistent. Crochet the swatch in the same mood and rhythm as the project, not in a rushed five minutes.
  • Check after washing. Some fibres relax or grow; the washed gauge is the one that matters.
  • Do not death-grip the hook. A tight grip usually produces tighter stitches and sore hands; loosen the grip before changing the hook.
  • Try a different hook material if the yarn drags or slips. Material changes the feel, not the millimetre size.

When the label and the pattern disagree

The yarn label suggests a hook range for a general fabric. The pattern gives a specific gauge for a specific fabric. Follow the pattern's gauge first, then use the label as a sanity check. If the pattern's gauge requires a hook far outside the label range, the yarn may be wrong for the project.

Check the hook, not the label

Two hooks marked G-6 can measure differently. If the gauge is far from the pattern and the stitch feels wrong, measure the shaft with calipers. A hook that has been dropped or worn may also be slightly out of size. The millimetre measurement is the reliable comparison.

When to change the yarn instead

If matching the gauge requires a hook far outside the yarn's suggested range, the yarn may be wrong for the pattern. A much larger hook can make a loose, floppy fabric; a much smaller hook can make it stiff. Change the yarn before forcing the gauge.

Limits

Gauge is a sample. Crochet tension can drift across a large blanket or garment, and the stitch pattern can change the fabric. Check the real project after the first few rows, while changing course is still cheap.

Compare hook size and tension, and use the crochet gauge guide for the fabric difference.

Sources