Mat-opening calculator
Calculate the visible window and the board-edge borders.
7.75 × 9.75 in
8 × 10 inch artwork · ⅛ inch overlap per edge.
A visual size estimate. Verify the actual artwork, frame, mat, glazing, hardware, wall and manufacturer specifications before buying or arranging a display. Dimensions alone do not guarantee fit.
Artwork, opening, outer board: three separate rectangles.
An 8 × 10 inch print does not necessarily need an 8 × 10 inch mat window. A small overlap covers the edges. Our initial ⅛ inch per-edge value is an editable example. Suppliers may specify ¼ inch or another amount.
Opening = artwork − (2 × overlap)
Side border = (outer board width − opening width) ÷ 2
Worked example: 8 × 10 in an 11 × 14 mat
With ⅛ inch overlap, the window is 7.75 × 9.75 inches. The horizontal border is 1.625 inches; the vertical border is 2.125 inches. The frame lip may hide part of those borders.
Check border conventions before ordering
A supplier can ask for artwork size, exact window size or mat size. Giving the artwork size in a field expecting an exact window could reveal a gap. Giving an already reduced opening in a field that automatically subtracts overlap could crop twice.
For several windows, use the multi-opening mat calculator. For example combinations, see mat and mount sizes.