Do not rely only on a product label
Print preparation guide
Measure a Mat and Frame Without Hiding the Artwork
Plan artwork overlap, visible window, mat borders, bottom weighting and approximate frame footprint before ordering or cutting a custom mount.
Quick answer
A window mat must overlap the artwork slightly on every edge, so its opening is smaller than the print. Add the visible borders to the window for the outer mat size, then confirm that board against the frame's actual inner rabbet—not only its advertised nominal size.
mat window = artwork size − two edge overlapsOverlap captures and hides the paper edge
The real frame opening is the final physical check
Decision table
Dimensions in a window-mat plan
| Layer | Based on | What it controls | Verify physically |
|---|---|---|---|
| Artwork | Actual paper edges | Starting width and height | Squareness and deckled edges |
| Window | Artwork minus overlap | Visible image and edge coverage | Subject is not hidden |
| Mat border | Window plus chosen margins | Visual spacing | Top, side and bottom balance |
| Outer mat | Complete board size | Fit inside frame | Rabbet clearance |
| Frame outside | Mat plus moulding | Wall footprint | Real profile construction |
Measure the object that will actually be framed
An advertised 8 × 10 print can differ slightly after trimming, and handmade or deckled paper may not be perfectly square. Measure width and height at more than one point and record which edge is the visual top.
Decide whether a signature, plate mark or paper edge should remain visible. A traditional overlapping window hides the edge; a float mount exposes it and needs a different support and spacing plan.
Make the window smaller than the artwork
Subtract the intended overlap from both sides of each dimension. An 8 × 10 inch print is 203.2 × 254 mm; with a 3 mm overlap on every edge, the window becomes 197.2 × 248 mm.
Too little overlap can reveal a white sliver or allow the artwork to fall through. Too much can cover signatures, borders or important detail. Cut a paper window template and position it over the work before committing valuable board.
Build visible borders from the window outward
Side and top borders can be equal, while the bottom is sometimes made slightly deeper so the opening feels optically balanced. This bottom weighting is a design choice rather than a fixed framing rule.
Add both side borders to the window width; add the top and bottom borders to its height. Those sums produce the outer mat dimensions, which must fit within the frame rabbet with the framer's chosen clearance.
Nominal frame size is not the outside footprint
A frame sold for an 8 × 10 item usually describes the item or opening it accepts, not the full wall footprint. The moulding extends beyond that inner size, and its rabbet lip hides part of the mat edge.
An outside-frame estimate is useful for wall planning and packaging, but the selected profile decides the exact result. Measure its inside rabbet, visible face width and depth before cutting glass, backing or mat board.
Protect the artwork with appropriate materials
Paper artwork can be damaged by unsuitable adhesive, moisture, acidity, pressure or contact with glazing. Valuable, original or irreplaceable pieces deserve advice from a qualified conservator or professional framer rather than an improvised permanent mount.
A mat creates visual spacing and can help separate work from glazing, but the complete conservation system also includes suitable board, reversible attachment, glazing, backing and environment. Geometry alone is not preservation advice.
Coordinate the crop and print before ordering the frame
If the final mat window uses a different aspect ratio from the image, preview which content will be hidden before printing. Add intentional image borders when they should remain visible and include them in the measured artwork size.
Calculate effective PPI from the printed image area, order the print, measure the actual delivered sheet and only then finalize a close-tolerance custom window. This sequence prevents rounding and lab trim differences from becoming a visible gap.
Practical workflow
Use this order before you export.
- Measure the delivered artwork at multiple points and decide which edges should show.
- Choose an overlap and test a paper window over the composition.
- Add side, top and bottom borders to calculate the outer mat.
- Measure the real frame rabbet and profile, then confirm materials and mounting with the framer.
Sources and method
Check the requirement behind the number.
These guides explain repeatable calculations and planning ranges. The print provider's written specification remains the final production requirement.
Put the guide into practice
Calculate the mat and frame geometry →Measure the real artwork, make the window slightly smaller, and fit the outer mat to the frame's actual rabbet.
Use the linked calculator with your own dimensions, then verify the result against the provider's production requirement.