A 4mm crochet hook is a US G-6. In UK sizing it’s a 8. I keep the mm number as my main reference for this size, since letter labeling is where most of the confusion happens between brands.
4mm to US letter, UK, and yarn weight
A 4mm crochet hook is a US G-6. In UK sizing it’s a 8. It’s typically used for DK to light worsted weight yarn, and I check the mm stamp on the hook itself whenever a pattern’s letter doesn’t match what I expect.
What projects use a 4mm hook
Match DK to light worsted weight yarn to this hook for the gauge most patterns expect, then adjust up or down a size if your own tension runs tight or loose. I always swatch first for anything that needs to fit.
Frequently asked questions
Is 4mm the same as G-6?
A 4mm crochet hook is a US G-6. In UK sizing it’s a 8.
What size yarn goes with a 4mm hook?
Dk to light worsted weight yarn is the usual match for this size.
See the full hook size chart
Compare 4mm against every other mm, US, and UK size in one table.