Picture Framing Calculator
Work out mat, glass and frame sizes plus the moulding to buy for a picture from the artwork size, mat border and moulding width. Calculates in your browser.
Mat & glass size
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Show the math
The mat window is cut a little smaller than the art so its edges don't slip through, then the border is added all around:
window = art − 2×overlap · mat outer = window + 2×border
The glass and backing match the mat outer size. The frame's outer size and the moulding to buy add the moulding face on every side, plus one face width per mitred corner:
moulding = 2×(mat W + mat H) + 8×face width
Add a little extra moulding for saw kerf and trimming mitres, and confirm the frame's rabbet is deep enough for glass, mat, art and backing together.
What this does
A picture framing calculator works out mat, glass, and frame sizes plus the moulding to buy from the artwork size, mat border, and moulding width.
How to use it
- Enter the artwork width and height.
- Set the mat border and overlap.
- Enter the moulding face width.
- Read the mat, glass, and moulding sizes.
How it works
The mat window is the art minus overlap on every side; glass and backing match the mat outer size. Add a little extra moulding for saw kerf.
moulding = 2 × (mat W + mat H) + 8 × face width
Understanding your result
The moulding figure is the length to buy, with a little added for the saw kerf at each mitre, so do not order exactly the perimeter or you will come up short on the last corner. The mat window is sized to overlap the art slightly so it cannot fall through, and matching glass and backing to the mat outer size keeps everything square.
Example
An 8 × 10 inch print with a 2-inch mat needs a 12 × 14 inch frame.
Sources & methodology
Last updated .
Frequently asked questions
Why is the mat window smaller than the art?
The mat overlaps the edges of the artwork so it doesn’t slip through the opening. We subtract the overlap on every side: window = art − 2 × overlap.
What size glass and backing do I need?
They match the mat’s outer size, which is the window plus your border on all sides.
How much moulding should I buy?
The frame wraps the mat outer perimeter and each mitred corner adds one face width: 2 × (mat W + mat H) + 8 × face width. Add a little extra for saw kerf and trimming.
Is my project saved?
No, all calculations run locally in your browser.
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