Printing Aspect Ratios and Sizes

One very important part of printing is making sure you use the right print size for the aspect ratio of your photo. The aspect ratio is simply the shape of the rectangle you have cropped your photo to. Trying to print your photo on the wrong shaped print size will result in you loosing part of your image in the new crop

Aspect ratios are expressed as two numbers which represent the long and short sides of the rectangle, usually written 2:3 or 4:5. These numbers tell us how many evenly sized squares you can fit into a given rectangle. For example 2:3 means you can fit a grid of squares 2 high by 3 wide in the rectangle and 4:5 means you can fit 4 high by 5 wide.

If this diagram you might notice that the 4:5 rectangle is closer to being square than the 2:3 which means that if your photo is cropped to 2:3 and you try and print it on a 4:5 print size you will loose some of your images length.

On this image you can see three different aspect ratios marked out on it. You'll notice that the 4:5 cuts off the edges of the graffiti and the 1:1 starts to cut into the Lego figure. 

Some printing places can do custom print sizes so you can make your print fit into the shape of your image's crop. However most print shops use standard print sizes which means you'll have to pick the print size that best suits your images crop. Here is a list of standard print sizes based on their aspect ratio.

2:3 Ratio

This is the default size of images produced by DSLR and some mirrorless cameras.

• 4 x 6 inch
• 8 x 12 inch
• 10 x 15 inch
• 12 x 18 inch
• 16 x 24 inch
• 20 x 30 inch
• 24 x 36 inch

3:4 Ratio

This is common in compact cameras and smart phones

• 6 x 8 inch
• 12 x 16 inch
• 18 x 24 inch

4:5 Ratio

This is an old standard used in large format film cameras.

• 8 x 10 inch
• 11 x 14 inch (it's not exactly a 4:5 ratio but it's very close and a very common size)
• 16 x 20 inch
• 20 x 24 inch

Other Common Ratios

Square crops, 1:1 ratios, are very common and you should be able to find square prints at most printing places but there are no 'common' sizes for these.

16:9 is a ratio used by a lot of smart phones and video cameras. It's the shape of modern TVs and is the most common shape for computer and smart phone screens. Not many printing shops will have 16:9 prints so if you want to keep this shape you may need to find a custom printer or print it on a 2:3 and trim the edges off.

Panorama prints are available in a lot of shops with ratios of 1:2, 1:3 and 1:4 being the most common.