Mat Board Opening Size

Dimensions for mat board openings can be very confusing. It is very counter intuitive, but the opening of a mat board should never be the same size as the photograph or print being framed. Usually it is a little smaller and sometimes it is larger, but not the same. Most pre-cut mats are cut 1/2 inch smaller than the photo print. That allows the mat to overlap the image by 1/4 inch on both sides. That brings up another confusing issue. If you want 1/4 of overlap the mat window must be cut 1/2 inch smaller and not 1/4 inch smaller because there are two sides. Personally I think 1/4 inch is too much overlap and so do most custom framers so the default for prints that are smaller than 18x24 is 1/8 inch overlap on Frame Destination pre-cut mats. For example, an FDI mat for 11x14 print would be cut to 10-3/4” x 13-3/4”.

Sometimes people will do what is called float mounting where the mat opening is larger than the image being framed. This is done to ensure that no part of the image is covered up and also to allow for a signature below the image. When doing this it is common to leave a 1/4 to 1/2 inch gap between the image and the mat board for the top and sides of the print. That means that width of the mat opening will be 1/2 to 1 inch larger than the image. When leaving room for a signature the bottom gap will usually be 1/2 to 1 inch. That results in the height of the mat being 3/4 to 1-1/2 inches larger than the visible part of the image.

Frame Destination, Inc.

About the author


Mark Rogers is an amateur photographer and the founder of Frame Destination, Inc. In 2004 Mark realized the framing industry was not keeping up with the evolution of photography via new digital technology and started Frame Destination in his garage. Now his company has thousands of do-it-yourself framing customers across the US that it helps with its 11,000 square feet production facility in Dallas, TX.

3 thoughts on “Mat Board Opening Size”

  • Carolyn

    I have a poster (10 actually) that is printed full bleed on 11 x 17 stock, i only want about 1/4 to 1/2 inch cover by the mat and I will put it in a barnwood frame. Do I need a mat opening of 10.5 by 16.5?
    and if the mat is 1 inch wide - wht is the opening of the frame. i know the width of the frame runners could be 1 to several inches but what is the opening? the poster is the banner on my website - the village of our carvings.

    • Mark Rogers

      If you make the mat opening 10.5 x 16.5 then the mat will cover up 1/4 inch on all 4 sides. This makes it easy to get placed in the mat but if you want more of the poster to show you can 10.75 x 16.75. Most frames overlap the mat by about 3/16 inch. 1" is kind of small. I would go at least 1-1/2 inch which results in the outer mat size and frame size of 13-3/4 x 19-3/4 if you go for the 10.75x16.75 opening.
      We have more info about frame dimensions here:
      Info about custom mats here:


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