This ratio means that an image’s width and height are equal, creating a square. The square format is the ratio of the classic Kodak image and is available as a choice in some digital and medium format cameras. It is popular with photographers using twin lens reflex cameras; medium format cameras that use 120 film rolled onto spools. Many Polaroid instant films were also designed as square formats. Additionally, it is the main aspect ratio for Instagram photos and is compatible with most social media sites.

SQUARE SIZES - 10 x 10 - 12 x 12 - 24 x 24

3:2 landscape orientation / 2:3 portrait orientation

This ratio is most widely associated with 35mm photography and is still one of the main aspect ratios for printing. Full-frame DSLRs and APS-C crop sensor cameras have 3:2 sensors. In situations where framing is more deliberate or where you have a primary and secondary subject, 3:2 works well. Where this aspect ratio may be underserving, is when you have too much free space in the sky or foreground. If you don't have a lot of details in the background or foreground, you may want to look at the 4:3 ratio.

LANDSCAPE SIZES - 18 x 12 - 24 x 16 - 36 x 24

PORTRAIT SIZES - 12 x 18 - 16 x 24 - 24 x 36

4:3 landscape orientation / 3:4 portrait orientation

This ratio is the most common aspect ratio in digital photography. Most mobile phone cameras (responsible for a majority of digital images today) use 4:3 sensors . In 2008 Panasonic and Olympus started to produce cameras in a micro four thirds standard that offer the quality of an SLR with the compactness of a point-and-shoot.

LANDSCAPE SIZES - 12 x 9 - 16 x 12 - 24 x 18 - 32 x 24

PORTRAIT SIZES - 9 x 12 - 12 x 16 - 18 x 24 - 24 x 32

4:5 portrait orientation / 5:4 landscape orientation

This ratio is most common in photography, art prints, large and medium format film cameras. This format, both film-based and digital, is still used for many applications such as landscape photography, advertising photos, fine-art photography, scientific applications and generally for images that will be enlarged to a high magnification while requiring a high level of detail.

LANDSCAPE SIZES - 10 x 8 - 20 x 16 - 30 x 24

PORTRAIT SIZES - 8 x 10 - 16 x 20 - 24 x 30