HOW TO MEASURE A SHIRT
How to Measure Chest
Measure your loose-fitting shirt across the chest; It may be the same or a different shirt than the one you used for the shoulder measurement. Button all the buttons on the placket. Lay your shirt face up on a rigid table and measure 1″ below the armhole to mark the 1″ point, then across the shirt (as shown above).
How to Measure Overall Length
To measure the overall length, measure the placket length. The placket is part of the shirt at the centre front with buttons and buttonholes. Measure from the neckband seam to the bottom hem. You can use a shirt you already own for measurement.
How to Measure Shoulders
Start with your loose-fitting shirt through the shoulders. Button all the buttons on the placket. As shown above, lay your shirt face down on a rigid table (not a bed or other soft surface). Measure from the shoulder point to the shoulder point.