Mine is at 24 inches not sure measurement is right . It is at least 22 inches though. Not lean but not sure it makes much difference here.
I looked at Darden article. Calling bs though see people much wider than me infrequently. They are usually much taller though.
My mum measured me with measuring tape with a bit of disdain lol. He uses callipers in the article. Not many people have them though.
131 cm or 51.57 in
I measure myself with my Hands close to my Body and without filling my Chest with air.
Oh sorry, Iām talking about girth and youāre talking about width. I havenāt measured the width.
I think you have measure from shoulder to shoulder not around the circumference i.e not your chest.
Yes, I fixed it 
Now I measured on a wall in my office /I marked with a pencil at each end/. About 22 in., with very small deviations. Arms close to Body with straight chest forward, but without puffing up like a bodybuilder. Normal upright body posture.
~0.72 doorframes. Average UK doorframe is 762mm
762mm = 30inches
72% of 30 = 21.6
~21.6inches.
About 22 inches I think.