What is an Aspect Ratio in Photography?

In this handy guide, we've outlined the basics of aspect ratio photography, so you can choose image dimensions that make sense for your overall composition.  
 
What is Aspect Ratio?
Essentially, aspect ratio photography boils down the width and height of your image into two number values. If your aspect ratio is 4:3, an image that's 4 inches wide will be 3 inches tall, and an image that's 8 inches wide will be 6 inches tall. No matter your image dimensions, the ratio stays exactly the same, and width is always written first.
 
Once you learn a few common aspect ratios, you can achieve a pleasing balance between your photographic subject and the empty space. Generally, your photographs shouldn't have too much empty space or an overwhelming amount of detail. In post-production, you can also crop a photo to delete empty space and change the aspect ratio. 
 
Here are the two most common aspect ratios in modern photography:  

  • 3:2: Used in most 35mm, DSLR, mirrorless, and prosumer compact cameras, the 3:2 aspect ratio was initially developed for Leica's 35mm cameras in the early 20th century. Even though the full-frame 35mm sensor is 36 x 24mm, you can simply those dimensions to a 3:2 ratio. Other camera brands may have a different sensor size, but the ratio stays the same.  
  • 4:3: This ratio is commonly found on medium-format cameras, micro four-thirds cameras, and digital compacts. 4:3 is slightly less wide than a 3:2 frame, so it leaves less empty space around your subject. It's also a favorite for landscape photographers.   

For more specialized purposes, you'll also find aspect ratios like 1:1 (square), 5:4, 7:6, and 16:9 (panoramic).
 
Adjusting Aspect Ratio in Editing Software
Even if you only have access to cameras that shoot in 3:2, it's easy to change an image's aspect ratio in Photoshop or Lightroom. 
 
To crop an image in Photoshop, just select the Rectangular Marquee tool, click on the Style menu in the control panel, and choose "Fixed Ratio". Then, enter Width and Height values for your desired aspect ratio. Draw a marquee on your image, and then choose "Image" > "Crop". 
 
Meanwhile, the cropping process is even simpler in Lightroom. Just click the Crop button in your toolbar (it looks like a dashed rectangle), and then choose an aspect ratio from the list. You can also choose a custom ratio by selecting "Enter Custom". 

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