Understanding Aspect Ratio

When offering printed photos to your clients, you are offering a level of service that other photographers may not provide. But this comes with its own set of challenges and requirements, and possibly changes in how you shoot and edit your images.

For a photo to look great printed, a few basic rules need to be met:

  • The photo needs to be technically sound- in sharp focus, with good exposure, color, contrast, etc.
  •  Your editing monitor needs to be calibrated for color.
  • The resolution and pixel dimensions must allow for images to be printed both small and large.
  • You must have an understanding of aspect ratio so that you may compose and crop your images accordingly.


Aspect ratio is the proportional relationship between the width and height of an image. Aspect ratio is expressed as two numbers separated by a colon, written as Width:Height or Height:Width. These numbers can be a specific unit of measurement such as inches or centimeters, but for the sake of simplicity, we can just refer to them as units.

Having a basic understanding of math and fractions will help you understand this.

A few examples:

  • A square is in an aspect ratio of 1:1; meaning both sides are equally proportionate, no matter what the actual dimensions are. A rectangle with an aspect ratio of 2:1 will have one side twice as long as the other side.
  • Many modern “widescreen” TV and computer monitors are in a 16:9 aspect ratio; it is 16 units wide by 9 units high. (This does not always mean that the TV must be 16 inches wide by 9 inches tall; the “units” can take on any unit of measurement and at any size.) TVs and computer monitors are usually referred to by their diagonal measurement from corner to corner, but a modern 21-inch monitor will have the same 16:9 aspect ratio as a modern 65-inch monitor, just in different overall dimensions. The aspect ratio for cinema screens has traditionally been 16:9, which is why modern TV manufacturers chose that aspect ratio. Older tube-style TVs and CRT computer monitors  were typically manufactured in a 4:3 or 5:4 aspect ratio, appearing closer to a square shape than a rectangle.
  • Most DSLR/mirrorless camera sensors are configured in a 3:2 aspect ratio, so your resulting images will be in a 3:2 aspect ratio before any cropping. A full-frame camera sensor (known as 35mm) measures 36mm wide x 24mm high. The largest number that both of these numbers can be evenly divided by is 8 (in math, this is the divisor), which will get us 36/8=3 and 24/8=2, or 3:2. A crop sensor camera has a physically smaller image sensor but it’s in the same 3:2 aspect ratio as a full-frame sensor.
  • Different types of cameras, such as point-and-shoot cameras and smartphone or mobile device cameras will often have different aspect ratios; my phone actually allows me to choose “widescreen” or “standard” aspect ratios when taking pictures. The aspect ratios on these devices will vary quite a bit depending on the individual brand or type of device, so there really is no standard.


Did I overload your brain yet with all of this math?

If you just skimmed over the previous few paragraphs, we will mainly be focusing on the 3:2 aspect ratio and how it relates to your photos and cropping for print. If you are shooting with a DSLR, SLR, or mirrorless camera, your camera probably defaults to shooting photos in this 3:2 aspect ratio (due to the sensor dimensions), so any print size you choose that is also in a 3:2 aspect ratio will not cause any part of the image to be cropped off. Print sizes that are in a 3:2 aspect ratio include 4×6, 6×9, 8×12, 10×15, 16×24, and 20×30. (Note that in the United States, typically the smaller dimension is listed first when referring to photo prints, so think of 3:2 and 2:3 meaning the same thing.) These print sizes will appear more rectangular. 4×6 and 20×30 are considered standard print sizes in the US, while these other sizes are not as commonly used for photos.

But what if you want to print a photo at a different size? Other standard print sizes include 5×7, 8×10, 11×14, and 16×20. None of these sizes are in the camera’s native 3:2 aspect ratio, and thus, some amount of the photo will inevitably be cropped or trimmed off of the long edge when printing. (Who thought of making these standard sizes anyway?!) For instance, an 8×10 is in a 4:5 or 5:4 aspect ratio; this is closer to a square than a 3:2 aspect ratio, and therefore part of the image will be trimmed off. A 16×20 print is also in a 4:5 or 5:4 aspect ratio, so even though the image will be considerably larger than an 8×10, the same parts of the image will proportionally be cropped off when printing.


In this example, I shot the image with enough negative space to account for print cropping at other aspect ratios. The 2:3 aspect ratio allows me to make a 4x6 print without any cropping, while other standard sizes will require some cropping.


Because a lot of photographers, especially when they are beginners, don’t always understand this at first, it amounts to frustration when trying to print an image as an 8×10 or 11×14 and notice that important elements in the photo are going to be cut off. These are just laws of physics and math, and there is no way around this.

So what can you do to maintain the look you want in your photos and keep your clients happy with their prints? A few things to keep in mind when shooting and editing:

  • Don’t shoot too close to your subject. Make sure you leave a comfortable amount of negative space around the subject, especially on the long edges, to account for cropping needs. Zoom out or take a step back before taking the photo.
  • Compose your photo so that no important elements are too close to an edge. Again, zoom out or take a step back.
  • Try to take a level photograph. When your photo is crooked, you’ll have to straighten it later, which will cause additional cropping.
  • During the editing process, resist the urge to crop your photos unless necessary. Leaving some extra room will allow for print cropping later.
  • Focus on selling print sizes such as 4×6, 6×9, 8×12, 16×24, and 20×30. These sizes are all in the native 2:3 aspect ratio, however, it may be less convenient when buying frames for the non-standard sizes.
  • Do not attempt to stretch or resize a photo to fit a print size that’s in a different aspect ratio. This will cause major distortion. 


Having an understanding and awareness of aspect ratios will allow you to create your art as intended and eliminate frustration with cropping needs, and therefore create more satisfaction for your clients.


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