Width: There is approximately a 1.25cm difference between widths (2A, B, D, 2E and 4E) and a 1cm difference between 4E and 6E width. This difference occurs across the ball of the foot and is the maximum difference in width. There is less of a width difference as you move toward the tip of the shoe and toward the heel.
Length: There is approximately a 4mm difference between each half-size (e.g., between 9 and 9.5, between a 9.5 and a 10, and so on). For every half size up, the width (across the ball) will increase by 3mm.
We cannot provide exact measurements for every style we produce, but we hope this general information is helpful.