@Qinhan:

Probably the safest bet.  Let us know how it works out!

10-4 will do!

@Qinhan:

I'm 5'9" and about 155 so it's pretty borderline…

Hmmmm.  Think I will roll with an M!  Thanks for all your input.  Pics really helped.

@Qinhan:

@wolfyb_:

@Qinhan:

As promised, a couple of fit pics.  These are just quick ones after I got home from work so the quality is pretty poor.

Fit is definitely more generous than the 13.  In comparison to the rest of my torso, I'm reasonably large in the shoulders but I don't feel at all constricted or tight when wearing this.

That looks good.  Thanks!  Think I could swing it now seeing that.

@Giles yup, first thing I always do!

Bonus pic for your consideration…

That's about the exact fit I'd want.  I'm 5'11" and about 160.  Think I should go M or S?

Thanks again for the pics.  Really helping to illustrate sizing.

@Qinhan:

As promised, a couple of fit pics.  These are just quick ones after I got home from work so the quality is pretty poor.

Fit is definitely more generous than the 13.  In comparison to the rest of my torso, I'm reasonably large in the shoulders but I don't feel at all constricted or tight when wearing this.

That looks good.  Thanks!  Think I could swing it now seeing that.

@Giles yup, first thing I always do!

@Qinhan:

My mistake.  I was confusing the 21 with the 13 (ie. the Western version of this shirt).

I also have the 21 in size small and the fit is more generous than the 13, which is what I was thinking of.  I don't have a pic of the 21 handy but might be able to take one later.

That'd be super helpful!  Kinda set on this one.  Seems the end-all be-all chambray shirt.  I appreciate it

@grandmasterben:

Do not get l. Even the medium will probably be bigger than your 40

Noted.  The shoulders throw me off!  Would S be too small, I mean going from 19 to 16.5 in the shoulders is a big jump!  Thanks for your advice!

G, in FH flannels I am a perfect 40, about 20" PTP.  Shoulders are about 18.5".

Should I get a M in this, considering the PTP measurement or should I get a L because of the smaller shoulders?