Many pros recommend subtracting 1/8" (about 3mm) from your final width and height to provide "fitting tolerance" so the glass isn't too tight to install.

Measure diagonally from corner to corner. If the two diagonal numbers differ by more than 1/4", your frame is "out of square," and you should consult the supplier before ordering. 💎 Step 2: Choose the Right Glass Type

Accurate measurements are the most critical part of ordering online, as custom-cut glass is typically non-refundable.