Understanding Mat Board Window Openings

Today, let’s talk about mat board window openings. It may not sound like an exciting topic, but understanding how to calculate mat board window opening sizes is a crucial skill for DIY picture framers.

The mat window opening, also known as the exact mat opening, is the opening that is cut in a mat board through which the image can be viewed.

Standard mat window openings are cut slightly smaller than the actual image size — this is called “cropping” the image. The opening is smaller in order to cover the edge of the image or any surrounding white border if it is a print. This is both an aesthetic (it looks better) and a practical choice; you don’t want the image to fall through the window opening if it’s cut too large!

Standard, off-the-shelf frames that come with mats usually crop ¼ inch on all four sides. Frame Destination cuts our popular size mat windows 1/8-inch smaller than the image to allow for maximum exposure of your image without a loss of detail. For images that are larger than 18” x 24”, our standard crop is ¼-inch.
Example: Your image measures exactly 8” x 10”. This is the actual image size, exclusive of any white borders, if it is a print. If you choose an 8” x 10” mat in one of our popular sizes, the actual window opening size will be 7 3/4” x 9 3/4”, which crops 1/8-inch of the image on all four sides.

Example: Your image measures exactly 8” x 10”. This is the actual image size, exclusive of any white borders, if it is a print. If you choose an 8” x 10” mat in one of our popular sizes, the actual window opening size will be 7 3/4” x 9 3/4”, which crops 1/8-inch of the image on all four sides.

If you prefer less or more cropping of the image, check the “customize this preset frame size” box and select your preferences. You can also always contact us for advice on the best mat window opening size for your artwork.