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Frame and Mat Size Calculator
Order the wrong frame size once and it’s a returned frame plus a second wait. Enter your art size and mat border and this gives you the exact mat opening, mat cut, and frame or glass size to order against.
Exact mat opening and outer mat size, not just a guess
Frame and glass size ready to order
Optional extra bottom weight for the classic gallery look
1
Measure your art
Width and height, in inches, edge to edge.
2
Set your mat border
How much mat you want showing on each side. 2 to 3 inches is typical for a standard frame.
3
Read the three numbers
The formula: mat opening = art size; outer mat and frame size = art size plus (2 x border). Add extra bottom weight for a heavier bottom border.
Quick reference: mat sizes for common art
Standard art sizes with a typical mat border, the pairings framers see most often.
| Art size | Mat border | Frame / glass size |
|---|---|---|
| 4x6 in | 2 in | 8x10 in |
| 5x7 in | 2 in | 9x11 in |
| 8x10 in | 2 in | 12x14 in |
| 8.5x11 in (letter) | 2 in | 12.5x15 in |
| 11x14 in | 2.5 in | 16x19 in |
| 16x20 in | 3 in | 22x26 in |
Museum matting? Add extra bottom weight, usually 0.25 to 0.5 inches more than the top and sides. It corrects an optical illusion where an equal-border mat looks bottom-heavy once hung. Float mounting? Skip the mat opening formula here; a float mount shows a small margin of backing around all four edges of the art instead of covering them, so the art size and mat opening are no longer the same number.
Frame and mat FAQs
What size frame do I need for an 8x10 print with a 2 inch mat?
A 12x14 inch frame and glass. The mat opening stays 8x10 to show the full print, and the outer mat, and the frame, both grow by the border on every side: 2 in times 2 sides adds 4 in to each dimension.
Why is the mat window cut smaller than my art size?
So the mat physically overlaps and holds the art in place, and covers any uneven edges. This calculator uses a standard 1/8 inch overlap on each side; custom framers sometimes use slightly more for delicate or valuable pieces.
What mat border width should I use?
2 to 3 inches is the standard, versatile choice. Smaller art, under 8x10, often looks better with a narrower 1.5 to 2 inch border; large statement pieces can carry 3 to 4 inches or more.
What is bottom weighting on a mat?
Extra width added to the bottom border only, so the top, left, and right stay equal while the bottom is slightly wider, usually by 0.25 to 0.5 inches. It corrects the optical illusion where an evenly bordered mat looks like it is sliding down.
Do I order the frame to the mat size or the art size?
The mat size, always, once a mat is involved. The frame and glass need to be exactly the outer mat dimensions; the art size only matters for the mat opening inside it.
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