What this Picture Mat Size Calculator does
The Picture Mat Size Calculator estimates the outside width and height of a mat opening arrangement from the artwork dimensions and a chosen border width. Enter the artwork's width and height, then choose the same border measurement for all four sides. The tool adds two borders to each artwork dimension, one at the left and right and one at the top and bottom. It then multiplies the resulting outside width by outside height to report the outside area in square inches.
This is a planning aid for visual design and craft work. It can help when sketching a paper mat, comparing proportions, or estimating how much rectangular mat board the outside dimensions cover. Its result is an area, so it does not state the outside width and height separately. You can still find those dimensions directly from the inputs. For an 8-inch-wide artwork and a 10-inch-tall artwork with a 2-inch border on every side, the outside size is 12 by 14 inches, and the reported area is 168 square inches.
The model assumes a rectangular artwork, equal border widths, and no additional frame allowance. It does not determine the visible opening, overlap behind the mat, bevel, frame rabbet, or material waste. Those details depend on the artwork and construction method, so treat this estimate as a first layout calculation.
How to use the Picture Mat Size Calculator
Measure the artwork itself and use consistent units. This configuration uses inches. Enter the width and height as decimal values if needed, then enter the border width you want on each side. The controls use quarter-inch steps, and their permitted values begin above zero, so each outside dimension remains positive.
- Artwork width: measure the horizontal dimension of the piece.
- Artwork height: measure the vertical dimension.
- Mat border: enter the desired distance from the artwork edge to the outer edge of the mat on each side.
Check that your measurements describe the artwork consistently. For a print with a paper margin, decide whether you are treating the full sheet or only the image area as the artwork, and use that same reference when planning the opening. A ruler is usually enough for a flat print. For an irregular or textured object, use the dimensions relevant to the mat design and verify the fit with a paper mock-up.
Worked example: enter artwork width 8 inches, artwork height 10 inches, and border width 2 inches. The outside width is 8 + (2 × 2), or 12 inches. The outside height is 10 + (2 × 2), or 14 inches. Multiplying those dimensions gives 12 × 14 = 168 square inches. The displayed result is Outside Area, with two decimal places.
How the Picture Mat Size Calculator formula works
The formula is (artwork width + 2 × border width) × (artwork height + 2 × border width). It first adds the left and right borders to the artwork width. It separately adds the top and bottom borders to the artwork height. Multiplying those two outside dimensions gives the rectangular area enclosed by the mat's outside edges.
For example, with a 5 by 7 inch image and a 1.5-inch border, the outside width is 5 + 3 = 8 inches and the outside height is 7 + 3 = 10 inches. The area is 8 × 10 = 80 square inches. The same border amount is applied on every side. This keeps the calculation transparent and easy to reproduce on paper.
Area can be useful for estimating the scale of a layout or comparing two proposed outer sizes. It is not the amount of board to purchase, since cutting can create waste and the final dimensions may need adjustment. It also does not describe the mat's opening. A physical opening is often planned to conceal a small part of the artwork edge, and the amount of concealment should be determined for the particular piece and mounting approach.
Use cases for the Picture Mat Size Calculator
In visual design, a mat border changes the balance between the artwork and its surrounding space. A wider border can give a small image more visual presence, while a narrow border can keep attention close to the image. The calculator helps translate that design choice into an outside area, making rough layout comparisons easier before cutting material.
For craft planning, use it to compare options for a print, illustration, photograph, or paper artwork. Try a few border measurements and note the resulting areas. This gives you a consistent way to compare proportions. You can also draw the outside rectangle at scale on scrap paper and place an artwork-sized rectangle inside it to preview the relationship.
The estimate can support a conversation about the overall footprint of a framed piece. If wall space or a shelf area is limited, calculate candidate outside areas and then check the actual width and height separately. Area alone does not reveal shape: a long narrow rectangle and a more square rectangle may have the same area but occupy space very differently.
Other factors to consider when calculating a picture mat
A real mat design has details beyond equal outside borders. The opening may be smaller than the artwork so that its edges remain covered. The exact overlap depends on how the artwork is held, whether it has a margin, and whether any edge contains important content. Measure and test the intended assembly before cutting a finished mat.
Some designs use unequal borders, such as a wider lower border for a visual effect. This calculator applies one border value on every side, so it cannot represent that layout precisely. For unequal sides, calculate the outside width by adding the left and right border measurements to the artwork width, and calculate the outside height by adding the top and bottom measurements to the artwork height. Multiply the two dimensions if an area estimate is useful.
Also consider the frame's fit, the thickness and condition of the artwork, and the method used to mount it. A frame's listed size may refer to the artwork it accepts rather than its outer dimensions. Confirm the relevant measurements from the frame or its product specifications. A test layout using inexpensive paper can reveal proportion or clearance issues before you cut mat board.
Frequently asked questions
Does the result give the mat's width and height?
The result is outside area in square inches. Find the outside width by adding twice the border width to artwork width, and find the outside height by adding twice the border width to artwork height. The example inputs of 8, 10, and 2 inches produce outside dimensions of 12 by 14 inches.
Does the border measurement include all sides?
The border input is the width on each individual side. The formula adds it twice to the artwork width and twice to the artwork height, accounting for the pair of opposite borders on each dimension.
Can I use different units?
This version is labeled in inches. If your measurements are in another unit, convert all three inputs to inches before entering them. Keep units consistent because the area result is the square of the length unit used.
Does the calculation size the opening?
No. It calculates the outside area using the artwork size and equal border widths. Opening dimensions and any overlap should be planned separately for the specific artwork and mounting method.
Can it estimate how much mat board to buy?
It gives the area inside the outside rectangle, which can help with an initial material estimate. It does not account for cutting waste, defects, bevels, or board sizes sold by a supplier. Check the planned dimensions and material requirements before purchasing or cutting.