Chronarch D7 and Curado E7 IPT

[Micropterus salmoides]

bantam1, I purchased the D7 for frogging and punching because of its 7:1 gear ratio and particularly its 30" IPT (inches per turn). Then I find out it actually has 28" IPT. I measured mine and it has 28.5" IPT. I'm curious, how did Shimano come up with 30" IPT? Does the Curado E7, another 7:1 30" IPT reel, really have 30" IPT? I'm thinking the difference may be because of the D7's narrow spool and that the E7 really has 30" IPT because of its wider spool.

[bantam1]

The IPT is based on a calculation using gear ratio and spool circumfrence. It can vary slightly due to line diameter and line capacity.