How to Measure a Shirt: Midsection Width
Spread the shirt out on its back such that there are no wrinkles or folds underneath. Find the narrowest part of the shirt’s body. This is probably about halfway between the armpits and the bottom of the shirt. Measure the width of the shirt at this point. This is not necessarily where the side seams are.
Tolerance:
While we do our best to sew each garment precisely to its specification every time, hand sewing and different fabric types naturally result in small variations. We consider a tolerance of +0.25” to -0.25” acceptable for the Midsection Width dimension.