How to Measure for a 24 Inch Picture Frame? | Get the Fit Right

Getting the right frame starts with one honest measurement: the exact size of the print or photo you want to hang. A “24 inch picture frame” refers to the inside opening that holds the artwork, not the outer edge of the moulding. Measure your piece correctly, and any standard or custom frame you order will fit the first time.

What Exactly Does a 24-Inch Measurement Mean?

How to Measure Artwork for a 24-Inch Frame

Lay the artwork flat on a stable surface and measure the visible image area edge to edge using a rigid ruler or tape measure. American Frame recommends working to 1/16-inch accuracy for the cleanest fit.

1. Place the artwork face-up on a flat, stable surface.
2. Measure the width first — the horizontal distance from left edge to right edge.
3. Measure the height second — the vertical distance from top to bottom.
4. Record both numbers in Width × Height format, such as 18 × 24 in.

Skip the borders, white margins, and any mount board unless you want those visible inside the frame. If the piece includes a signature that should stay in view, measure to include it.

Measuring an Existing Frame or Adding a Mat

If you already own a frame and want to know what size art fits it, flip the frame face-down and measure the inside opening from inner edge to inner edge. This “rabbet” measurement is the space the artwork actually sits in; the exterior dimensions tell you nothing useful for choosing new prints.

Adding a mat changes the math entirely. When you frame a smaller piece inside a 24-inch frame, the visible area is the mat’s window opening, not the full mat board. Measure that window, then choose a frame size that accommodates the mat’s outer dimensions plus the artwork.

Common Sizing Mistakes to Avoid

• Measuring the outside frame edge instead of the inside opening.
• Including white borders or mat margins you don’t want visible.
• Guessing the size instead of measuring the actual print.
• Confusing frame size with mat opening — the window is always smaller.
• Ignoring aspect ratio, which crops the image if the frame’s proportions don’t match the art.

One more thing to check: thick canvases and layered mats need a frame deep enough to hold them. Width and height get you the right size, but rabbet depth determines whether the art actually fits inside. When in doubt, measure the artwork’s thickness and compare it to the frame’s listed depth before ordering.

Ready to sort through your options? See our roundup of the best 24 inch picture frames for tested recommendations.

FAQs

Should I measure a poster with its white border?

Only if you want that white margin visible in the finished frame. Most posters look better trimmed or matted so the printed image defines the display area. Measure the image itself, then decide whether a mat adds the border you want around it.

What if my artwork is slightly larger than the frame opening?

Trim the print, order a custom frame, or add a mat that reduces the visible opening. Forcing oversized art into a smaller frame causes buckling and damage.

Does frame depth matter for standard prints?

Not usually. Standard paper prints and posters fit fine in regular-depth frames. Depth only becomes critical for stretched canvases, thick mat stacks, or artwork with mounted objects — those need a frame with enough rabbet depth to hold the extra thickness.