Crochet I hook in mm measures 5.5mm, sitting one size up from the more common H hook at 5.0mm, often used for a slightly looser worsted weight fabric or a snugger bulky weight project. An I hook is the next step up whenever an H feels a touch too tight for a specific yarn. This guide gives the direct size.
Direct Answer
The I hook measures 5.5mm, commonly used with worsted to light bulky weight yarn for a slightly looser drape than an H hook produces with the same yarn.
Frequently asked questions
What yarn weight pairs best with an I hook?
Worsted to light bulky weight yarn typically pairs best with an I hook, giving a slightly looser, drapier fabric than the same yarn would produce with a smaller H hook.
Want the full hook size chart?
See every standard hook size in millimeters at a glance.
See the full hook size chart
