I've used Sagulator many times over the years, it's a helpful tool. I've always wondered, however, why it doesn't allow for both front AND read shelf edging instead of just front edge in calculating sag. I've built many wide floating shelves where the recommended edge stiffener is too tall, reducing vertical shelf access. To mitigate this, instead of of a single tall shelf edge I've applied shorter strips to both front and rear edges. However, it's always a guess and it would be great if Sagulator were to add this calculation to their on-line tool.
Also, unless I've overlooked it they don't specify whether the shelf edge stiffener is intended to be attached to the side edge of the shelf or to the shelf underside. This matters since adding the stiffener to the front edge would typically require a narrower shelf, whereas placing the stiffener on the underside wouldn't affect shelf width. For example, if my shelf is 18" deep and I intend to add a 3/4 x 1.5" stiffener to the shelf edge, I would have to rip 3/4" off the shelf to arrive at the desired 18" width with the edging added....17 3/4 + 3/4 edging. Some time ago I was discussing this with a friend and his approach was to first determine the desired edging width using Sagulator and then dividing that in 2 to determine the front and rear edging strip widths. I have no idea if that makes sense from an engineering standpoint but it seems to work. Anyone have insight on this?