Shell Measuring Caliper

Using a caliper makes it easy to measure a shell opening. The upper "inside diameter" prongs are great for measuring empty shells. The lower "outside diameter' prongs can be used to measure the opening size of a shell with your hermit crab in it. Just position the lower prongs on either side of your crabs' body and line the edge of the prong up with the edge of the shell opening.

Our Shell measuring Caliper is designed to make it easy to determine the proper size of shell opening your crab needs.

Calipers are a useful and accurate way to measure inside and outside diameters but are typically hard to read. We have taken a lightweight polycast caliper that is designed to measure down to 1/128", and applied a custom easy to read sticker that is graduated every 1/8". The measurement is read below the 0 (1 1/2" in the picture above).

We measure all of our shell openings from left to right and list them by opening size in 1/8" increments, so using this caliper will help ensure that you get the shell size you desire.