How to Calculate Mat Borders for an Existing Frame

Choose the matboard’s actual outside size to fit your frame, subtract the artwork overlap to find the window, then divide the remaining board width and height between the four window borders. A shop label alone is not enough to establish the frame’s actual inside dimensions.

For an 8 × 10 inch image and an 11 × 14 inch board, 1/4 inch overlap on each edge leaves a smaller window. You can center the window or shift it upward by increasing the bottom border while keeping the board size fixed.

Calculate the window and all four borders

1. Establish the board size. Measure the existing frame’s back rabbet recess, or confirm the dimensions of a correctly fitting glass/backing piece. Leave the fitting space required by that frame. Logan’s measuring guide describes checking the back recess and allowing room around the components.
2. Decide what the mat may cover. Here the artwork area is 8 × 10, not a larger paper sheet. Subtract twice the overlap on each axis. The engine gives a 7 1/2" × 9 1/2" window.
3. Center horizontally. Window-border left + right = board width − window width. Equal sides are (11 − 7 1/2) ÷ 2, giving 1 3/4" on each side before the frame covers the mat.
4. Choose the vertical position. Top + bottom window borders total board height − window height. A centered window has 2 1/4" at both top and bottom. The pictured bottom-weighted option redistributes that space to 1 3/4" top and 2 3/4" bottom.

Artwork border, window border and visible border

The Studio fields measure from the artwork edge to the board edge. Subtract overlap from a desired window border to get the value to enter. In the pictured design, the 1 3/4" side window border corresponds to a 1 1/2" artwork-border input.

The installed visible mat border is narrower where the frame lip covers the board. Measure the actual sight opening to assess that effect; do not subtract a guessed lip width from a retail label. The 11 × 14 label, board outside size, mat window and frame outside size are distinct measurements.

The 1/4 inch overlap here is an example choice. Frame Destination’s opening specifications use other allowances for some prints. Check the image edges and any signature rather than assuming all pre-cut mats use this example’s opening.

Enter this design in Studio

The example button imports the forward-calculated inputs; it does not measure or reverse-solve an existing frame. In Artwork, enter your image dimensions. In Mat, select Single, set the four artwork borders and check overlap under Advanced. Verify the package readout equals your planned board size.

The imported frame uses an example moulding and depth. Enter your existing frame’s measured face, lip and rabbet depth before relying on its outside dimensions, wall preview or stack-fit result.

For the centered alternative, keep the side inputs at 1 1/2 inches and set the top and bottom artwork borders to 2 inches in Studio. For bottom weighting, redistribute the top/bottom pair instead of simply growing the bottom of an already fixed board. This keeps the outer board size unchanged.

Common mistakes

• Using an 8 × 10 window for an 8 × 10 image, leaving no overlap.
• Entering window borders into Studio without subtracting the overlap.
• Assuming an 11 × 14 nominal frame means an exactly 11 × 14 back recess or outside size.
• Increasing the bottom border without reducing the top when fitting an existing board.

Use the corresponding tool

Check a mat window and board from artwork borders

Use the tool to check your arithmetic, then edit the four borders in Studio. Read how opening and outside frame dimensions differ if the frame’s label is unclear.

This recipe covers a rectangular, overlapped single mat. It does not cover floating a full sheet, oval/multiple openings or a conservation mounting method.