Matting sizing can seem tricky but we are here to try and make it as simple as possible for you.


Mat size- Refers to the outside dimensions of the mat and typically refers to the size frame it will fit in.  For example, an 18x24 mat, measures 18" x 24" on the outside

Picture Size- Picture size is the general reference for what the opening of the mat is cut to.  For example, a 16x20 mat for an 11x14 picture, tells us that the opening has been cut to overlap an 11x14 picture.  Typically, the opening is 1/4" smaller than the picture size all the way around.  See below for reductions.

Opening Size- Refers to the actual opening of the mat.  So again, if you have a 16x20 for an 11x14, the actual opening will be 10.5 x 13.5 to overlap your 11x14 picture.

Standard Mat Sizes, Picture Sizes and Openings:

  • 24x36 for 20x30 picture Actual Opening= 19.5x29.5
  • 22x28 for 18x24 picture  Actual Opening= 17.5x23.5
  • 22x28 for 16x20 picture  Actual Opening= 15.5x19.5
  • 20x24 for 16x20 picture  Actual Opening= 15.5x19.5
  • 18x24 for 13x19 Picture    Actual Opening= 12.5x18.5
  • 18x24 for 12x18 Picture    Actual Opening= 11.5x17.5
  • 16x20 for 11x14 Picture    Actual Opening= 10.5x13.5
  • 11x14 for 8x10 Picture      Actual Opening= 7.5x9.5
  • 11x14 for 8x12 Picture      Actual Opening= 7.5x11.5
  • 8x10 for 5x7 Picture        Actual Opening= 4.5x6.5
  • 5x7 for 4x6 Picture         Actual Opening= 3.5x5.5