How To Measure For A 24×36 Picture Frame: Sizing And Matting Guide

Buy the wrong frame and a poster worth framing comes back creased. The measurement step most people skip — actually sizing the artwork, the mat, and the frame as three separate numbers — decides whether the piece fits or gets returned. Whether a mat enters the picture changes every number that follows.

How To Measure For A 24×36 Frame The Right Way

Measure the artwork edges with a ruler, never the packaging or a listed nominal size. Prints sold as “24×36” can run slightly under or over, and a frame cut to the label rather than the paper is where fit problems start.

From there, the math splits by whether the piece will be matted.

• No mat: a true 24×36 print drops straight into a 24×36 frame.
• With a mat: the frame must be larger than the artwork so the mat borders stay visible.
• Mat opening: cut about 0.25 inches smaller than the artwork on each side, so the mat overlaps the edges and holds the print flat.

Gallery One’s mat measurement guide and Patchogue Arts’ framing presentation both work from that same overlap logic — the mat opening is deliberately undersized, not an exact match.

Standard US frame sizes commonly sold include 4×6, 5×7, 8×10, 11×14, 16×20, and 24×36 inches, and 24×36 doubles as the standard poster size for movie posters and large prints. Logan Graphic’s complete framing guide lists 24×36 among those standard sizes and confirms it works as a direct-fit print size. Once you know which of those two roles you need — a tested 24×36 frame for your print — the fit math becomes simple arithmetic rather than guesswork.

Why Your 24×36 Frame Won’t Fit A Matted Print

The frame’s visible opening is smaller than its listed size, because the rabbet — the inner lip that holds the glass and backing — overlaps the edge by a fraction of an inch. A “24×36 frame” rarely displays a full 24×36 inches of artwork once that lip is accounted for.

That overlap is the single most common cause of a print that measures correctly but still won’t sit right. Add matting to the equation and the shortfall compounds, since the mat needs its own border space inside the frame.

Three assumptions cause nearly every bad order:

1. Expecting a 24×36 frame to hold a 24×36 print plus a mat. It won’t — the mat needs extra room, so the frame has to be larger than the art.
2. Treating the nominal frame size as visible display area. The rabbet takes a bite out of it.
3. Measuring from the packaging or a printed label instead of the actual paper edges.

There’s a naming trap buried in all of this, and it explains most of the confusion. “24×36” describes a frame size in some listings and a print size in others. Distinguish art size, mat opening, and frame size explicitly before ordering, because the three numbers are rarely identical.

Mat Opening Sizes That Actually Work

Add a small border and the common math produces a 23.5×35.5 opening inside a larger frame like 28×40. For a 20×30 print, pre-cut mats typically run 19.5×29.5 inside a 24×36 frame.

Exact dimensions shift with the frame’s rabbet depth and the mat’s outside measurement, so manufacturer specs and product style always get the final word. Order the mat from the same spec sheet as the frame when you can, and confirm both numbers match your measured artwork before checkout.

Handling comes down to one practical risk: an incorrect size means a returned order or, worse, a print bent during a forced fit. Measure twice, and never trim artwork to make it work — trim the mat instead.