What Size Mat For A 24×36 Frame? | The Real Fit Rules

A standard 24×36 inch frame cannot hold a mat and a true 24×36 artwork because the frame’s lip cuts the visible area to roughly 23.5 x 35.5 inches; to display a 24×36 print with a mat border, you must jump up to a larger frame like 27×39 or 30×40.

That big 24×36 movie poster or art print you just bought is about to hit a sizing trap. A “24×36 frame” is measured by its internal rabbet — the groove that holds the glass and backing — not by the space your image actually gets. The frame’s lip overlaps the edges, reducing the viewable window to roughly 23.5 x 35.5 inches. That means a true 24×36 piece with a mat simply won’t fit inside a standard 24×36 frame. Here is exactly how mat sizes work for this common format, whether you want to keep things cheap or build a gallery-grade display.

Why A 24×36 Frame Can’t Mat A 24×36 Print

The frame industry labels a frame by the size of its rabbet — the inside groove that holds the glass, art, and backing. For a 24×36 frame, the rabbet is exactly 24 x 36 inches. The lip that overlaps the glass (called the rabbet overlap) reduces the visible area to about 23.5 x 35.5 inches. A mat board eats up part of that depth too. So if your artwork is a true 24×36, there is no room for a mat frame.

You have two real paths:

• No mat, same frame: Put the 24×36 print directly inside a standard 24×36 frame. The frame lip will overlap the edges by roughly 0.25 inches on each side. That is normal and most affordable.
• Add a mat, bigger frame: Buy a frame larger than 24×36 and pair it with a custom mat cut to a 23.5 x 35.5 opening.

Pre-Cut Mat Options For A 24×36 Frame

If you already own a 24×36 frame and want to mount a smaller print with a mat, pre-cut mats made for this frame size are widely available. These mats fit the frame’s outer rabbet and leave a clean border around your image.

The two most common pre-cut mats for a 24×36 frame are:

These mats are acid-free, white-core, 4-ply boards with a bevel cut. They cost $10–$25 depending on material and brand. Amazon carries “24×36 Mat for 20×30 Photo” options that are ready to drop into your existing frame.

Frame Sizes That Accommodate True 24×36 Art With A Mat

If the artwork itself is 24×36 and you insist on a visible mat border, you need a larger frame. The mat opening for any of these frames should be cut to 23.5″ x 35.5″ (0.25 inches smaller than the art on each side) to hold the print firmly behind the mat window.

Standard frame sizes that work:

• 27×39 frame: produces a roughly 1.5-inch mat border around the art.
• 27×40 frame: a slight vertical offset; common for certain poster series.
• 30×40 frame: the classic gallery standard. Creates a generous 3-inch border on each side, giving the piece visual breathing room.
• 28×40 frame: less common but available from specialty retailers.

Among these, the 30×40 frame is the most cost-effective option for a clean museum-grade look. Glass and molding costs stay reasonable, and custom mat boards up to 32×40 inches are easy to source.

If you are looking for something in the 24×32 territory, our roundup of the best 24×32 frames covers tested options at various price points.

How To Calculate The Mat Opening For A Custom Cut

The formula is simple: subtract 0.25 to 0.5 inches from both the width and height of your artwork. That extra overlap lets you tape or hinge the print to the back of the mat without the edges showing through the window.

Step-by-step:

1. Measure the artwork exactly with a metal ruler. Art paper and prints often vary slightly from the stated size.
2. Subtract 0.25 inches from the width measurement. That is your mat opening width.
3. Subtract 0.25 inches from the height measurement. That is your mat opening height.
4. For a 24×36 print, that gives you a 23.5 x 35.5 inch opening.

Some cutters, like Frame Destination, use a 1/8-inch offset for prints under 18×24 to show more of the image. But for a 24×36 piece, 0.25 inches is the standard across most manufacturers and is safer for proper overlap.

Mat Board Sizes And Custom Cutting Limits

Standard blank mat boards top out at 24×36 or 24×24 square for off-the-shelf purchases. For a larger frame like 30×40, you need a custom-cut mat from a 32×40 blank board. Providers like Matboard Plus cut custom mats up to 32×40 without major price jumps.

Once you go beyond 40 inches in either dimension, material costs spike and available options thin out. Stick with a 32×40 maximum blank size unless you have a specific custom need.

Art materials should always be acid-free (pH neutral) to prevent yellowing and chemical damage over years of display. Standard 4-ply white-core mats from reputable suppliers meet this requirement.

24×36 Mat Size At A Glance

The table below covers the most common scenarios so you can find your match fast:

Common Mistakes That Waste Time And Money

The biggest error is assuming a 24×36 frame can fit a 24×36 print AND a mat. It cannot — the lip overlap plus mat thickness makes the assembly impossible to close. You will either bend the backing or crack the glass.

Another frequent slip is ignoring the “quarter-inch rule” when ordering a custom mat cut. If you order the opening at exactly 24×36, the art has nothing to hold it in place and will shift behind the window. Always go 0.25 inches smaller on each side.

Finally, avoid ordering a mat board over 40 inches unless you have a specific large-scale project. Costs rise sharply, and most residential frames never need that size.

Final Fit Checklist

• Measure your artwork with a ruler, not the packaging.
• Decide: no mat (use 24×36 frame) or mat (upgrade to 27×39, 30×40, or 28×40).
• For a mat, order the opening 0.25 inches smaller than the art on each side.
• Pick acid-free, 4-ply white-core board for longevity.
• Stick to 32×40 max blank size for affordable custom cutting.