Name each rectangle
The sheet size is the full piece of paper, including any printed border. The image size is the area containing the picture. The mat opening is the visible window cut into the mat. The frame's fitting size is the size of the assembly it accepts, and the outside size includes the molding. A product page may show several of these without explaining their relationship.
For example, a frame sold as 11 by 14 inches with a mat for an 8 by 10 print generally holds an 11 by 14 mat and backing. The mat window is commonly slightly smaller than the nominal print size so its edges overlap the sheet. You should confirm the actual opening before assuming that every part of an 8 by 10 image will remain visible.
Measure the object you own
Lay a stable, replaceable print on a clean support and measure its full width and height without dragging a ruler across the image. Then note the image area separately. A seller's nominal size may include a white border. If the image itself is 8 by 10 inches on a larger sheet, a frame designed to accept an 8 by 10 sheet will not hold the whole paper.
Do not trim a signed border, deckled edge, or unidentified older print merely to fit a ready made frame. Choose a larger frame with a suitable mat, or ask a framer to measure and propose an appropriate package. A different frame is easier to reverse than a cut sheet.
Include depth and hardware
A frame can be wide enough but too shallow for the intended mat, glazing, backing, and spacers. Look for its usable fitting depth, sometimes called rabbet depth. The depth visible from the side is not necessarily all available for the contents. Check whether the retaining clips can close correctly with the proposed assembly.
Also confirm whether the frame hangs vertically, horizontally, or both. A tabletop frame may have a stand that prevents a neat wall fit. Supplied hardware may suit the empty frame but still needs to be considered with the final glazing and contents. Record the total finished weight before selecting wall attachments.
Use outside dimensions for the wall
Make the wall template from the outside measurement. Two 11 by 14 frames with different moldings may have noticeably different outer footprints, and neither may align with a neighboring frame that has the same label size. When buying several, compare the visible opening, outer dimensions, and hanging points rather than the large number on the box alone.
If the description is unclear, send the seller your sheet dimensions and ask which size the listing names. A short written confirmation can resolve whether the product is sized for a bare print, a matted print, or the complete frame before you place the order.
