Measure the artwork itself
Lay the piece flat and measure width first, then height. Measure the paper or photo—not an existing frame. For irregular art, record the smallest rectangle that contains it.
Measure once, frame well
Picture frame size guide
A frame label describes what goes inside—not the finished outside edge. Use these four steps before ordering.
Choose direct fit or a mat
Match the labeled frame size for a direct fit. For visual breathing room, choose a larger frame and a mat opening that overlaps the artwork by 3–6 mm per edge.
Calculate the frame size
Add the visible mat border twice to both artwork dimensions. Treat the result as a target, then choose a standard frame or custom mat that preserves the proportions.
frame = artwork + (2 × mat border)Check the product listing
Verify the usable opening, included mat opening, outside dimensions, rebate depth, and seller tolerances before ordering.
Worked example: a 5 × 7 photo
A common ready-made combination uses an 8 × 10 frame and a mat opening cut just under 5 × 7.
5 × 7 artwork+mat border→8 × 10 frame
Four mistakes to avoid
Most wrong-size orders come from mixing up measurements, not difficult arithmetic.
Measuring an old frame
The outside edge includes moulding and cannot reveal the artwork size that fits inside.
Matching frame to mat opening
The frame matches the mat outside size; the smaller opening matches the artwork.
Ignoring aspect ratio
A 4 × 6 photo and an 8 × 10 frame have different proportions. A custom mat can absorb the difference.
Assuming every listing is identical
Nominal sizes, openings, depths, and manufacturing tolerances vary between sellers.