HCA: Hermit Crab Association

Hello,
I'm new to having a hermit crab and have questions regarding the shell size. My hermit crab changed his shell before he molted for the first time that lasted for 2 months and it's been a little over a month that he surfaced. I'm unsure of what size shells I should have out for him now should I add the same size shell he's in now or add shells 1/4 larger or a mix?

A mix is best, some crabs like a loose fit while others like to be tucked in tight.

For shells under 1 inch opening, 1/4 inch increments in size is usually perfect. For shells over 1 inch opening, a smaller change of 1/8 or even 1/16 is often enough because the interior volume increases faster, and too much of a jump can be too big and heavy to carry.

Thank you.