A 3mm aluminum hook (in the U.S.) would probably be a C hook. (Hook sizes are not always the same when made by different manufacturers.) Fingering or sock yarn would be best suited to this size hook. That said, manufacturers generally note the suggested hook size on the label of the yarn. That is a suggested size only and you are free to choose a different size hook with which to work that yarn. Also, your pattern will likely tell you what size hook to use and the appropriate yarn for your project.
If you are looking at steel hooks, you would have a size between a 1 and 0 hook which would be used for thread, probably size 5.
it is best to use an H or I size hook
that would be a size P crochet hook
You should use a size J/10 crochet hook for a project that requires a 6 mm crochet hook.
The recommended size of crochet hook for working with yarn that is 5mm thick is typically a 5mm crochet hook.
A 00 crochet hook is typically around 9.0 millimeters in size.
For yarn, use an "E" or an "F".
The recommended size of crochet hook in the US for working with a 3mm yarn is typically a size C or D hook.
You should use a crochet hook that is labeled as 5.00 mm for the project.
For this project, you should use a size 6 yarn crochet hook.
Projects that are best suited for a 2.5 mm crochet hook size are typically intricate and delicate items such as lacework, amigurumi, and fine garments like shawls or baby clothes.
To effectively use a 9mm crochet hook in your projects, start by choosing the right yarn weight for the hook size. Maintain consistent tension while crocheting to ensure even stitches. Practice proper hand positioning to avoid strain. Experiment with different stitch patterns to see what works best with the larger hook size.
A 5.0mm would be an H-8 hook.