What brands do you wear? Someone may have the same and be able to compare them for you.
I have a Castelli jersey in M. It is ok.
The Jerseys from the "Drei Länder Giro" in Austria, the size M was the last two times rather to loose. I have ordered for this year the size S. The years before M was perfect. (it seems that the size is growing.).
The jersey from "Ötztaler Radmarathon" in Austria last year (a cuore jersey) I have ordered in S. It is perfect.
The jersey from the "Charity Bike Cup" in Heimerdingen (a renerosa jersey) was S. But it is to small!
Northwave M is ok.
Jersey from "Schwarzwald Ultra Marathon" (a Maisch jersey) M is ok.
Thanks for your support!