*all measurements in inches
How to measure your button down
To measure chest width - Lay shirt flat on a table (with all buttons fastened) and measure from seam at armpit to seam across the chest.
To measure length - Lay shirt flat on a table and measure from below collar seam to bottom of shirt.
To measure sleeve - Lay shirt flat on a table and measure from shoulder seam to edge of sleeve.
See photo for detailed illustration arrows where to measure from.