Measuring casing on your own can be a bit tricky sometimes. Here’s a trick I learned early on that made it a lot easier. (1) Measure the distance from the outside of the jamb to the outside of the opposing side. (2) Subtract the thickness of both sides of your jamb, while leaving the reveal you want. For example, my jamb was a total of 1” thick, so I subtracted 3/4” to leave a 1/8” reveal around my window jamb. This will give you your inside measurements for your mitres. (3) After cutting my fir