Dimensions Guide

When you’re taking pictures, knowing something of the photo sizes is a must. As you shoot images, being aware of the ratios used by the cameras will be helpful.

Camera and Photo Ratios

Most digital cameras today use the 3:2 ratio for the images they take. In simple terms it means the long side is 1.5 times longer than the short one. This corresponds to the 4 x 6 print size, which is why its use has become widespread.

For ordinary photo editing, this is all right. But the ratios for other print sizes are not the same. Used incorrectly, the image will be cropped.

For example, print photo sizes measuring 5 x 7 or 8 x 10 have different ratios from the 4 x 6. The 5 x 7 ratio is 3.5:2.5. This means the long size is 1.4 x the short side. The 8 x 10 has a ratio of 5:4. This means the long side is 1.25 times longer than the short one.

How the Ratios Affect Photos

Suppose you’re shooting a photo to be made a portrait and it’s going to be enlarged. When using different formats, you’ll have to make allowances on the long side; this will prevent the image from being cropped. The 8 x 10 format makes it easy to crop images. It’s also worth noting that most prints don’t fall below the length multiplication of 1.25.

Common Print Sizes and Their Length Multiples

When studying photo sizes, keep the following figures in mind: 4 x 6 – 1.5, 5 x 7 – 1.4, 8 x 10 – 1.25, 10 x 13 – 1.3 and 11 x 14 – 1.27. Other common print sizes are 10 x 20 – 2, 16 x 20 – 1.25, 20 x 24 – 1.2 and 20 x 30 – 1.5.

Other photographic print sizes are 3R (3½" × 5"; 9 cm x 13 cm), 4R (4" × 6"; 10 cm x 15 cm), 4D (4½" × 6"), the 5R (5" × 7"; 13 cm x 18 cm) and 6R (6" × 8"; double the 4R). The print photo size 8R (8" × 10"; 20 cm x 25 cm) is also well known.

Ohter Sizes

Other sizes are S8R (8" × 12"; "20 cm x 30 cm), 10R (10" × 12") and the 11R (11" × 14"; 28 cm x 36 cm). The 6R measures 6" × 8", while the S10R is 10" × 15" (equivalent to 254 × 381 mm). The S11R is 11" × 17" while the 12R is 12" × 15". The S12R is 12" × 18".

The Super sizes use a ratio of 3:2. Keep in mind that the print names may vary per region. In Japan for example, the print sizes are prefixed with letters. The 4R is KG, the 3R is L, 5R 2L and so on.

Only a few of these photo sizes are used by causal photographers. But if you want to take stock of all your options, knowing these dimensions will come in handy.