Short answer
Back width drafted to the lats with reach room tested in the fitting.
Why it happens
Lat spread wider than the chest measure implies.
Why ready-to-wear cannot fix it
Size charts grade uniformly; muscular back is a personal geometry. A block adjusted in one place pulls in another — which is why the correction must exist in the pattern, not in the fitting-room mirror.
How the house drafts for it
Back width drafted to the lats with reach room tested in the fitting. The correction is recorded in your Fit Passport, so every later commission starts from it automatically.
Where it matters most
This correction carries most for: suit, shirt, blazer. It is reviewed at every fitting, in every city, for every garment.
Fit Library entry 34 of 48 · Reviewed by Bonturberg Editorial Review · 2026-09-08