How to Choose a Frame Mat for a 5×7 Photo? | Mat Size Rules

Choose a mat opening of 4.5 x 6.5 inches for a 5×7 photo, leaving a 1/4-inch overlap on every side to hold the print securely.

Getting the mat size wrong is the most common framing mistake. Cut the window too large and the photo slips or shows gaps; cut it too small and you crop the image. The rule is simple: the opening must be slightly smaller than the print so the mat overlaps the photo’s edges and holds it in place. For a 5×7 print, that means a 4.5 x 6.5 inch opening, typically paired with an 8×10 outer mat.

This guide covers the exact measurements for a 5×7 photo, how to calculate border widths, and the common mistakes that ruin a finished frame. If you’re ready to buy instead of cut, our tested roundup of the best 5×7 frames with mats shows pre-cut options that skip the measuring entirely.

What Size Should the Mat Opening Be?

The mat opening for a 5×7 photo should be 4.5 x 6.5 inches. That gives you a 1/4-inch overlap on each edge, which is the sweet spot framers use to keep the print secure without covering too much of the image.

The overlap is not optional. A mat cut exactly to 5×7 leaves the photo unsupported — it can fall through the window or show a thin gap at the edges. Logan Graphic, a leading mat-cutting manufacturer, recommends at least 1/8 inch of overlap per side in its picture framing guide, with 1/4 inch being the common default. For most home framers, 1/4 inch is the safer choice because it tolerates slight paper expansion or a photo that was trimmed unevenly.

Ready-made mats follow this same logic. A standard 8×10 mat board with a 4.5 x 6.5 inch window is the most widely available pre-cut solution for a 5×7 print. Buy that combo and the math is already done for you.

How Do You Calculate the Outer Mat Size?

Start with the opening, then add your border widths to get the outer dimensions. The opening is determined by the photo; the outer size is a style choice.

Here is the calculation for a 5×7 photo with a 1/4-inch overlap and 2-inch borders on all sides:

• Opening width: 5 inches minus 1/2 inch (1/4 inch per side) = 4.5 inches
• Opening height: 7 inches minus 1/2 inch = 6.5 inches
• Outer width: 4.5 inches plus 4 inches (2 inches per side) = 8.5 inches
• Outer height: 6.5 inches plus 4 inches = 10.5 inches

Those outer dimensions don’t match a standard frame size, which is why the 8×10 setup exists. An 8×10 outer mat with a 4.5 x 6.5 window gives you roughly 1.75 inches on the sides and 1.75 inches on top and bottom — slightly uneven but visually balanced and compatible with off-the-shelf frames.

What Border Width Should You Choose?

Professional framers generally recommend a mat border of 2 to 4 inches. For a small print like a 5×7, 2 to 3 inches is the standard range; larger artwork calls for 4 inches or more. The border should also be wider than the frame moulding itself — a thick frame with a thin mat looks cramped.

Gallery One’s mat measurement guide and Logan Graphic’s learning center both treat border width as style guidance rather than a fixed rule. A 2-inch border looks clean and modern; a 4-inch border gives the piece a more formal, gallery-style presence. The one hard constraint is that the mat border must be wide enough to look intentional — anything under 1.5 inches reads as an error rather than a design choice.

Common Mat-Sizing Mistakes to Avoid

Most framing failures trace back to a handful of recurring errors. Here is what to check before you cut or order:

• Cutting the opening to 5×7 exactly. This leaves the photo unsecured and exposes raw edges. Always undersize by at least 1/8 inch per side.
• Confusing outer mat size with opening size. A “5×7 mat” in a product listing can mean a 5×7 outer board (for a 4×6 photo) or a 5×7 opening (for a 5×7 print). Verify which measurement the seller means.
• Ignoring the frame rabbet. Logan Graphic notes the rabbet — the lip inside the frame — must be slightly larger than the combined thickness of the mat, glass, and backing. Stack all three before assuming they fit.
• Skipping the actual measurement. Print shops sometimes trim photos slightly, and paper can vary. Measure the print you actually have, not the size you ordered.

When buying a ready-made frame with mat, all four of these issues are already resolved — the mat, glass, and backing are cut to match each other. That’s the practical route for most people, and our roundup of the top-rated 5×7 frames with mats covers the options worth buying.