How do i choose the diameter of the contacts?

If you are new to contact lenses, we strongly advise you to get a small diameter as start, so that you will get use to it. You may choose from 15mm and below.
If you are experience in wearing contact lenses, you can choose any diameter lenses. Take note that huge diameter lenses such as 22mm (aka sclera lenses) may not fit everyone well, even though you are expert in handling contact lenses