To get the width, measure from left to right, jamb to jamb.

How to measure jamb depth. This measurement is to tell you how thick the. For height, measure from the. Standard door casing is typically 2 1/4 inch wide, and about 5/8 inch thick.

Make note of the largest of the three measurements just in case the. Do it at the top, middle and bottom of the jambs to get three width measurements. Trim around a jamb is typically referred to as door casing.