UK crochet guide. Written in British English, with UK stitch names and metric measurements.
A hook marked “4” needs a second look. Does it mean 4 mm, an older UK size number or a number within a different manufacturer’s system? The missing unit matters more than the number itself.
For a modern UK project, record the millimetre measurement whenever it is available. It gives you a clearer reference when the next tutorial, shop or hook brand uses different labels.
Use the metric size as your common reference
Some US hooks carry a letter and number as well as millimetres. The Craft Yarn Council notes that letter and number designations can vary by company. Check the package measurement instead of relying only on a conversion remembered from another hook.
| Metric measurement | Common US designation |
|---|---|
| 3.5 mm | E-4 |
| 4 mm | G-6 |
| 4.5 mm | 7 |
| 5 mm | H-8 |
| 5.5 mm | I-9 |
| 6 mm | J-10 |
This short table is a reference for common regular hooks. It is not a universal guide for every brand, historical hook or fine steel crochet hook.
An old UK number is not a millimetre size
A vintage pattern may specify a numbered hook without using millimetres. Read the publication’s tool key and check the intended sizing system. Do not replace “No. 8” with an 8 mm hook simply because both contain an eight.
If the conversion is uncertain, look for the stated tension and yarn description. These help you test the intended fabric, although an unusual historical material may still require more research before you can reproduce the design accurately.
The yarn band and pattern have different jobs
The hook suggestion on a ball band gives a starting point for using that yarn. The pattern’s hook and tension describe a particular fabric. A dense small object and a draping scarf can use the same yarn differently.
Also check whether the band shows knitting needles rather than a crochet hook. A needle-size recommendation is not a crochet measurement just because it is printed beside a 10 cm tension square.
Compare like with like when testing
Use the specified crochet stitch, make a sample larger than the measurement area and count through the middle. Let it relax and follow the appropriate care instructions before deciding whether the hook produces the required tension.
If you change hook style or brand partway through a project, compare a small section before continuing. Hooks with the same stated diameter can feel different in the hand, and your working tension may change with that feel.
What if the size marking has worn off?
Use a suitable hook gauge or compare with a clearly labelled equivalent, following the measuring tool’s instructions. Do not estimate the size from the handle thickness: an ergonomic handle can be much wider than the working shaft.
Label the storage space or keep the hook with a project note once you identify it. A short note is particularly useful for hooks whose printed markings disappear with use.
Buy for the next project, not for an imagined collection
A large set can be useful later, but a beginner can start with the hook needed for one clear lesson and a suitable yarn. Notice grip comfort, how the head passes through the loops and whether the size is easy to read.
Keep the hook size in millimetres beside the yarn name and sample measurement. If a pattern also gives a letter, copy that as supporting information. The metric record makes it easier to return to the project without guessing what “the green hook” meant.
Where to go next
Build a small starter kit · Choose DK yarn · Compare UK and US stitch names