Proper Mat Size for Matting an Image

Framing sounds simple on paper, but it’s trickier than you may think. Determining the proper mat size and mat opening for a print or photograph is one of the more confusing issues facing novice framers.

First, be sure you understand the two different measurements associated with matboards. There is the overall mat size, which is the outside measurement of the mat board.  Then, there is the mat window measurement, which is the size of the opening in the mat through which we see the image.

In this article, we’ll talk about how to properly measure the mat dimensions. We’ll also venture into the World of Basic Math, as some of us may need a little refresher. 

Measure the Dimensions

To determine the overall dimensions of the mat, measure the glazing size (size of the glass or acrylic) of the intended frame. If the glass fits inside the frame without too much wiggle room, then it’s a good template for cutting the mat to its overall size.

For the mat window size, one general rule is that the window should not be the same size as the print or photo. Cutting a mat to the exact dimensions of the outer border of a picture or photograph is almost impossible and it is just as difficult to get them lined up perfectly.

Off-the-shelf, picture frames usually have pre-cut mat boards with openings that are half an inch smaller than the intended picture size. For example, a 16″ x 20″ frame that includes a mat for framing an 11″ x 14″ print or photograph will have a mat window opening somewhere in the neighborhood of 10 1/2″ x 13 1/2″.

This result is the mat overlaps each side of the print by 1/4 inch. A quarter of an inch does not sound like much on its own, but it adds up since every mat has four sides. The overlap is desired to help keep the art in place within the frame.

How Large Should the Mat Border Be?

One of the most common questions from DIY framers is how large should the mat border be? While we can make suggestions, the answer is: However big you’d like! As a general guideline, the mat should be at least 1.5 times the size of the frame to keep the frame from overpowering the artwork. Adjusting the size of the visible mat will dramatically change the appearance of your art, so it’s important to have an understanding of the desired final look.

Best Practice for Frame Mat Size

Many professional framers, including Frame Destination, recommend a mat border of 2 to 4 inches (unless you have a specific look in mind that calls for a wider or narrower mat). This provides the “traditional” framed look with a mat border that is equal on all sides and doesn’t overwhelm the art.

If your art is smaller, you may want to opt for a border that is closer to 2 inches to avoid overwhelming the artwork. Larger framed pieces can support wider mat borders while still retaining that classic framed look.

Frame Destination can custom cut a mat to any size, so you're not restricted to a standard frame size.

It’s also important to consider the color of the mat you’ve chosen. You can display a large amount of a neutral color mat board without it overwhelming and distracting from the art, but if you’ve opted for a bright, rich or bold colored mat, you may want to consider a narrower border.

More Mat = More Impact

When putting together a framed photo or piece of art, three major components will affect the look and feel of the final piece:

• The art
• The frame
• The mat

In traditional framing practices, the mat plays a supporting role. But there may be times you want the mat to have a much bigger impact. Large mat borders can give your art a “gallery” look, drawing more attention to your art if you’re displaying it on a large wall.

Opting for a weighted mat (where one or more sides has a wider mat border) is another popular option. Taking weighting to an extreme is a popular modern look that pairs well with black and white photography. You can choose from many mat board styles to give your art the look you want.

Using bright or bold colored mats is another way to add impact to your art, particularly for black and white photos. Mat board is available in just about every color of the rainbow, so you’re not limited to earth tones or neutrals when framing.

Adding Depth Without Size

If you want to add depth, character, or color to your mat without overwhelming the art or opting for a large mat border, consider layering mats. In a layered mat situation, two or three mats (often of different colors) are framed. The top layer is the most visible, while you’ll see smaller amounts of each of the lower layers.

This technique allows you to add some depth to your framing or introduce a touch of color. For just subtle color pop, choose a neutral or subtle top mat, then select a bold or bright hue for the second layer. This technique is ideal when you want to highlight a color featured prominently in the art, but don’t want a full-color border. To highlight more than one shade, opt for a triple mat with a neutral top and colorful second and third mats. Or you can achieve a modern look by layering white-black-white mats.

For depth without color, opt for mat layers that are the same shade or have slight variations within the same palette. This will give you a tiered look without adding more color.

Layered mats can be as large as you’d like, so you can use this technique with large borders or with the traditional 2- to 4-inch mat border.

How We Do It at Frame Destination

At the end of the day, how big your frame border is depends on personal preference and your desired look. When you order a mat board from Frame Destination, you can play with the sizes to see how your art will look with its new mat. You can even upload your image for a preview and change the colors of the mat and frame to see all your options before you buy.

We carry several varieties of mats, including 100% cotton, acid-free, and lignin-free mats with solid color throughout. Some of our mats trap and neutralize pollutants and acid by-products. All our mats feature larger windows than most store-bought mats, meaning more of the image shows through in a framed piece.

Standard mat window openings usually overlap the art between 1/8 inch or 1/4 inch. This overlap helps hold down the artwork and keep it in place, so you don’t have to worry about the mounting board showing in the finished framing package. Our website allows you to customize your mat window opening to overlap your art more, or less if you desire.

Matting for a Float Mount

Although allowing the mat to overlap the image is the most common matting technique, sometimes using a mat opening that is larger than the image, known as “float mounting,” works best. This matting technique prevents any masking (or covering) of any part of the framed image. It is especially useful when you want the ability to view the artist’s signature or print data.

There are several ways to accomplish this look, including using different overlap measurements on different edges of the work. Usually, the side and top border measurements are between 1/4 to 1/2 inch and the bottom is expanded to reveal between 1/4 and 1 inch of the border. In most cases, the bottom dimensions of a mat are equal to the top and sides, but the presence of a signature changes that. Getting it right requires a little math along with some good measuring skills. Beyond that, a common mistake is to forget to double the border size when calculating the opening.

For example, if the signature is shorter than 1/2 inch, you can use 1/4-inch or 3/8-inch top and side borders with a slightly larger 1/2-inch bottom border. If the signature has a height of 3/4 inch, you can use 1/2-inch top and side borders. In this case, the mat opening will be 1 inch larger than the image width, and 1 1/4 inches larger than the image height.

Sometimes drawing out a sketch prior to making any cuts helps better visualize your goals. Beyond that, never forget that the adage “measure twice, cut once” doesn’t just apply to carpentry.

A Short Detour to Mathville

Some of us break out into a cold sweat at the mention of the “m” word, but don’t be afraid! Making artwork is a passionate endeavor and one that doesn’t necessarily lend itself to precision. Art often ends up in non-standard, custom sizes. Or in the case of specialty paper with exposed deckled edges, it takes a bit of finagling to order the right mat boards and framing. 

If you are in the United States, a country that uses the English ruler as the standard system of measurement, learning how to read a ruler will help you measure your art accurately so that you can order the proper-sized mat boards and picture frames.  

So, let’s talk about the English ruler and how to read one. And let’s address fractions, which are a defining component of the English ruler, and how to work with fractions in the context of picture framing.

What is an English ruler? English rulers provide incremental measurements in inches, with each inch further divided into smaller and smaller fractions. 

What are fractions? Fractions are a visual representation of the parts of a whole. For example, a whole pie can be divided into fractional pieces such as 1/2, 1/4, 1/8, etc., depending on how many people you need to serve (and how hungry they are).

• Fractions consist of a numerator and a denominator.  

• Numerator: the top number, which equals the number of parts out of a whole. 

• Denominator: the bottom number, which shows the total number of equal parts an item is divided into.

How do you read a ruler for English measurements? English rulers or English tape measures are marked at different levels of precision. The diagrams below illustrate how to read them from various precision levels. 

Below is a ruler marked in 8ths. Every mark is 1/8 of an inch.

This ruler is even more precise, marked in 16ths. Every mark is 1/16 of an inch.

The center mark between numbers is 1/2 inch. The highlighted lines on these rulers are marked at 1/2 inch and 1 1/2 inch.

The next smallest marks are 1/4 inch. The highlighted lines on these rulers are marked at 1/4, 3/4, 1 1/4, 1 3/4 inch.

The next smallest marks on a ruler are 1/8 inch. The highlighted lines on these rulers are marked at 1/8, 3/8, 5/8, 7/8, 1 1/8, 1 3/8, 1 5/8 and 1 7/8 inch.

The next smallest mark, if there are any, are 1/16 inch. The highlighted lines on this ruler are marked at 1/16, 3/16, 5/16, 7/16, 9/16, 11/16, 13/16, 15/16, 1 1/16, 1 3/16, 1 5/16, 1 7/16, 1 9/16, 1 11/16, 1 13/16, 1 15/16 and 2 1/16 inch.

Shortcut for “inches.” From here on, we’ll use the double straight quotation mark (″) to refer to inches. 

How do I add/subtract fractions? In framing, you will typically be working with fractions with the same denominator. 

For example: 

We need to add two measurements: 3/16″ + 9/16″. 

Step One: 

Since we have a common denominator (16), we add the numerators (3 and 9):

3/16 + 9/16 = 12/16

Step Two: 

Simplify the final fraction by reducing it to the lowest term. Find the Greatest Common Divisor (GCD) — aka, Greatest Common Factor (GCF). 

Common Divisor: a whole number that can evenly divide two or more numbers.

Greatest Common Divisor (GCD): the largest number among the common divisors of two or more numbers. 

In the example of above, 12/16, both the numerator (12) and the denominator (16) are divisible by 2 and by 4. Always divide using the largest possible number, in this case 4.

12 ÷ 4 = 3

16 ÷ 4 = 4

= 3/4 

Your final measurement is 3/4".

Real World Framing Example with on Floating Artwork

My image size is 4 1/2″ W x 3 1/2″ H.

I want to add a 1/2″ border all the way around my image; the image plus that border will be my mat window opening. REMEMBER: Because a frame has four equal sides, whatever you add to one side needs to be doubled!

Width: 

4 1/2″ W

1/2″ x 2 = 1″  (doubling the 1/2″ border)

4 1/2″ W + 1″ = 5 1/2″ W

Height: 

3 1/2″ H

1/2″ x 2 = 1″ (doubling the 1/2″ border)

3 1/2″ H + 1″ = 4 1/2″ H 

Your mat window opening would be 5 1/2″ W x 4 1/2″ H.  

If you need help with calculating fractions, this fractional calculator can save the day: https://www.calculatorsoup.com/calculators/math/fractions.php. 

What fractional level does Frame Destination cut materials to? 

At Frame Destination, we use the English ruler system, and we work with fractions at a precision level of 1/16″— 1/16, 2/16 (= 1/8), 3/16, 4/16 (= 1/4), 5/16, 3/8, 7/16, 8/16 (= 1/2), 9/16, 10/16 (= 5/8), 11/16, 12/16 (= 3/4), 13/16, 7/8, 15/16.  

What can I do if I have a complicated piece of artwork that’s hard to measure? 

If you need help with measuring, and/or calculating your fractional mat board measurements, trust us, you’re not alone. Please feel free to contact us at 972-479-1188 or sales@framedestination.com.

In Praise of Mats

Mats are an integral part of framing. Practically, mats help keep the framed image flat, and provide a buffer layer between the art or photo and the frame glazing. Aesthetically, mats help accent the framed item, presenting your art at its best and creating a unique look. Depending on the mat’s composition, it can even help preserve your artwork.

In other words, getting matting right may not always a piece of cake, but it’s always worth it!

Frequently Asked Questions

How Much Matting Should Be Around a Picture?

The amount of matting around a picture depends on several factors such as the purpose of the mat, the size of the picture, the frame, and aesthetic preferences. In general, matting serves to enhance the artwork and create a buffer between the art and its frame, protecting the piece from any moisture or direct contact. Typically, a mat can be anywhere from 1.5" to 4" or even wider, depending on the size of the artwork and the desired effect. However, it's essential to strike a balance; too much matting might overpower the artwork, while too little may not provide enough protection or visual appeal.

What if the Frame is Too Big for the Picture?

If the frame is too big for the picture, several solutions can be considered. One can use matting to center and accentuate the artwork, bridging the size gap between the image and the frame. Alternatively, options like a floating frame can be employed, where the picture appears suspended with space around it. If aesthetics are significantly impacted by the size discrepancy, one might choose to add decorative backing, create a collage with other images, or even opt for a different frame that better complements the picture. The objective is to ensure the artwork is enhanced and not overshadowed by the framing choice.

Written by Mark Rogers

Mark Rogers is the President and Co-Founder of Frame Destination. With over 20 years of experience in the field, Mark has become a leading authority on framing techniques and best practices, and has earned a reputation for his innovative approaches to custom framing and frame services for photographers and artists.

Updated September 29, 2023