The ball girth is the measurement around an the shoe last.  The Ball Girth is measured around the last from the lateral ball point to the medial ball point.  When measuring a last you need to know the ball girth. The ball girth of a last typically grades at a rate of 1/4 per whole size or 6.35mm per size.

The ball girth is the measurement around the shoe last from the lateral ball point to the medial ball point. When measuring a last you need to know the ball girth. The ball girth of a last typically grades at a rate of 1/4 and 6.35mm per whole size.