In order to prevent the glazing/artowrk fall out from the frames all the frames (except canvas frame) have an internal lip to support the glazing/artwork
Hence, front the front view, about 5mm per side of your artwork will be covered by the lip.

Frame with multi opening
-> lay and flatten your artwork at a flat surface as you want to see them in frame (row and column)
-> take the masurements of width and height in milimeters
-> the actual size of the window of mount will be deducted 2.5mm each side to allow you to stick the picture in splace and prevent falling out from the mount
-> input the measurements to your chosen product and get preview of the fame

Canvas
-> lay and flatten your artwork at at flat surface
-> take the measurements of width and height in milimeters
-> input the measurements to your chosen product and get preview of the frame
-> if you have a canvas need to be stretched, the actual size of the wrapped canvas will be deducted 30mm each side for the depth of the canvas.