I'm building a web site that will allow users to upload photos. For design and layout purposes, I need to know the most common aspect ratios users will upload. What is the most common aspect ratio of photos (e.g from dSLR, smart phones, etc.)?
The two most common aspect ratios for digital photography are 4:3 and 3:2. You will also see a significant number of 1:1 (square) photos and 16:9 ("widescreen") images.
3:2 is the aspect ratio of 35mm film cameras, and that has carried over to most DSLRs, both the APS-C size and "full-frame". Most compact digital cameras, along with the Micro Four Thirds interchangeable-lens mirrorless system, use 4:3.
Most smartphones are also normally 4:3, but popular apps like Instagram produce square 1:1 images, so you can't discount that. And, the HDTV-like 16:9 aspect ratio is a common option in many cameras of all types (usually but not always just by cropping off the top and bottom of each image in-camera).
It would probably also be wise to consider the possibility of arbitrarily-wide panoramic images, as many cameras (both via apps and just as a feature) have the ability to produce those very easily. And, of course, you really shouldn't discount cropping, both to historically-standard ratios like 8:10 and 5:7, and completely arbitrarily.
And keep in mind that you will also see these turned the other way: 3:4 and 2:3 for portraits; 9:16 looks odd and is less likely, but the theme here really is that anything goes.
This is all off of the top of my head, but if you'd like the referenced and researched background on these aspect ratios and other common ones found in photography, see my answer to What historic reasons are there for common aspect ratios?
Most of my users will be using a digital camera (they will be taking photos of products they are selling). So, should I be focusing on 3:2 or 4:3? Jan 21, 2013 at 6:52
I think you reasonably need to cover both, but if you're sure that DSLR users will be in the minority you can probably get away with a focus on 4:3.– mattdmJan 21, 2013 at 7:05
No, DSLR will be in the majority. Jan 21, 2013 at 7:07
2In that case, go with 3:2. That's the ratio used by Canon, Nikon, Pentax, Sony, and Sigma DSLRs. Only those from Panasonic and Olympus use 4:3 (and the latter companies are now focused on their non-DSLR system cameras).– mattdmJan 21, 2013 at 7:10
10Keep in mind that photos can be portrait orientation as well. Then they are 2:3, 3:4 and so on. It's frequently overlooked by our graphics designers as well. Jan 21, 2013 at 22:32
If it's any help, I just queried all photos I've taken over the past many years and here's the first 25 results:
Results will be from many different cameras and taken by a few different humans, but me and my friends/fam of course do not represent the entire human population.
1This answer would be better if you condensed the rows that are clearly the same aspect ratio (or at least nominally the same). For instance, 1.33333 and 0.75 are the same aspect ratio, 4:3 (the only difference is orientation: the first is landscape, the latter is portrait). Same with 1.5 & 0.666667 (3:2). Also, all of the 1.50-ish ones are all nominally 3:2.– scottbb ♦Jan 13, 2021 at 17:36