Why Frame Depth Matters: A Key Element in Professional Picture Framing

When framing artwork, photographs or keepsakes, most people focus on style—choosing the right frame color, material or design to match their décor. However, there’s a structural detail that plays a vital role in both the appearance and protection of what you're framing: frame depth. Often overlooked, frame depth determines whether your item fits securely and stays well-preserved over time. It’s not just about how the frame looks from the outside but how it functions from the inside.

Frame depth refers to the space inside the frame where the contents sit—this includes your artwork, mat board, glazing (glass or acrylic) and backing. When you select a frame without considering this measurement, you risk damaging your piece or ending up with an unstable fit. Whether you're framing a print, canvas or 3D object, knowing the correct depth ensures both professional results and long-term preservation.

What Is Frame Depth?

Frame depth, also called rabbet depth, is the internal measurement from the front edge of the frame (where the glass rests) to the bottom ledge (where the backing board sits). It determines how thick your contents can be before they stick out or become improperly sealed.

For example, a basic photo frame might have a rabbet depth of 1/4" to 3/8", just enough to hold a print, glass and backing board. But if you're framing a canvas or multiple layers with matting and spacers, you’ll need a much deeper rabbet to accommodate everything safely. Choosing the right depth means your framed piece will sit flush and feel solid—without gaps, pressure points or movement inside.

Why Depth Matters for Different Materials

Not every item you frame has the same thickness. A flat photo and a stretched canvas behave very differently once inside a frame. That’s why the frame depth must match the material you're working with.

• Photographs and posters are generally thin and can fit into shallow frames. But if you’re adding mat boards or multiple layers, you’ll need extra space.

• Canvas paintings need deeper frames because the stretcher bars can be 3/4" to 1.5" thick or more. If the frame isn't deep enough, the canvas won’t fit properly and it may bulge or protrude.

• 3D items or shadowboxes, such as souvenirs, crafts or textiles, require significant depth to create space for mounting without pressure or crowding.

Using a frame that matches your material’s thickness prevents damage and gives you the flexibility to enhance the display with mats or spacers.

Impact on Appearance and Protection

The right frame depth doesn’t just help with fit—it also affects the look and durability of your framed item. A frame with proper depth allows each component—glass, mat, artwork and backing—to lie flat and stay protected without shifting or warping over time.

When artwork touches the glass, moisture can get trapped and cause condensation, mold, or sticking. But with enough depth, you can use spacers or matting to create a gap between the art and the glazing. This extra space helps with air circulation and keeps your piece in good condition, especially for delicate materials like photographs or watercolors.

From the front, the added depth gives your frame a clean, structured appearance. Nothing looks crammed or misaligned and the contents sit naturally inside the frame—just like they would in a gallery or museum.

Choosing the Right Frame Depth

Selecting the right frame depth starts with measuring the total thickness of everything you plan to frame. This includes:

• The artwork or object

• Any mat boards

• The glazing (glass or acrylic)

• The backing board

Once you add these together, choose a frame with a rabbet depth that’s slightly larger than your combined materials. This gives you room for secure fitting and additional hardware like turn buttons, clips or frame points.

For canvases or thick art, deep-set frames or canvas floaters are often the best choice. If your item is flat but you want to include layers for a more dimensional look, you’ll also benefit from added depth—even if the piece isn’t thick on its own.

When in Doubt, Ask a Framing Expert

Not sure if your frame depth is right for your project? Don’t guess—ask a professional framer. They can help you choose the right frame based on your item’s size, thickness and long-term display needs. Expert framers will also recommend the best materials for mounting and sealing, which helps preserve your piece and maintain its condition for years.

They can even build custom frames to your exact depth specifications, especially useful for artwork that doesn’t fit standard sizes or for special keepsakes you want to protect in a shadowbox.

Final Thoughts

Frame depth is one of the most important details in picture framing—even though it’s often overlooked. It affects how well your contents fit, how protected they stay and how clean your final display looks. Whether you're framing a simple photo, a thick canvas or a keepsake collection, choosing a frame with the right depth ensures everything stays securely in place and maintains its appearance over time.

A shallow frame might work for a flat print but for anything thicker or layered, you’ll need a deeper rabbet to avoid damaging your items. By understanding frame depth and selecting your frames carefully, you’ll achieve not just a better look—but longer-lasting results too.

If you’re unsure where to start or need help choosing the best frame for your artwork, don’t hesitate to consult a framing expert or explore our blog for more custom framing tips and inspiration.