Picture Frame & Mat Calculator

Find the mat board size and the outside frame dimensions you need for a photo or artwork. Enter the artwork size, the mat border you want on each side, and the frame moulding width.

Standard frame and mat sizes

How it works

Mat board outer size = artwork + 2 × mat border on each dimension. Outside frame size = mat outer size + 2 × frame moulding width. For example, an 8 × 10 in print with a 2 in mat and 1 in frame gives a 14 × 16 in mat and a 16 × 18 in frame.

When to use this calculator

• Framing a print, poster, certificate or original artwork.
• Deciding how wide a mat border should be before ordering a custom frame.
• Checking whether a standard frame size can accommodate the artwork plus a mat.
• Planning multiple framed pieces that need to look consistent on a wall.

Worked examples

• 8 × 10 in artwork, 2 in mat, 1 in frame: mat outer 12 × 14 in, outside frame 14 × 16 in.
• 11 × 14 in artwork, 3 in mat, 1.5 in frame: mat outer 17 × 20 in, outside frame 20 × 23 in.
• 16 × 20 in artwork, 2 in mat, 1 in frame: mat outer 20 × 24 in, outside frame 22 × 26 in.
• 5 × 7 in photo, 3 in mat, 1 in frame: mat outer 11 × 13 in - close to a standard 11 × 14 frame with a slight difference to confirm.

How wide should a mat be?

A common guideline is a mat border of about one third of the shorter artwork dimension for small pieces, then widening gradually for larger works. In practice, 2–3 inches suits prints up to 11 × 14 in, while 3–4 inches suits larger artwork. Mat borders that are too narrow make the piece look cramped; very wide mats can overwhelm small prints unless the wall space calls for it.

Frame size versus opening size

Retail frames are usually described by the size of the opening they accept, not the outside dimensions. An "11 × 14 frame" normally takes 11 × 14 in artwork or a mat that is 11 × 14 in overall; the outside frame is roughly 2–3 inches larger depending on the moulding. When in doubt, measure the opening, not the outer edge.

Common mistakes

• Adding the mat width only once instead of on both sides of each dimension.
• Forgetting that the frame moulding adds width on the outside as well.
• Buying a frame by its outside size and finding the opening too small.
• Ignoring the extra depth needed for a double mat and backing board.

Related tools

Common print sizes chart · Print size calculator · Canvas vs poster vs photo print