To explain, first lets look at a finished page detail. Note that each photo square is sized to one inch. Between each square there is an eighth inch gap.
The Mosaic Moments Cutting Mat is printed with a coordinating system. Thick lines are printed at one inch marks. Thinner lines are printed every eighth inch.
click on image to see larger view:
So, when you want to cut photos to cover more then one square the rule is you will always have one less gap then you will squares.
cover 1 square width = 1 inch
cover 2 square width = 2 1/8 inches (count 2 thick lines and 1 thin line.)
cover 3 square width = 3 2/8 inches (count 3 thick lines and 2 thin lines.)