The size of a 7-inch photo is 5 inches by 7 inches.

every inch is 2.54cm, which is 12.7 * 17.78cm..

example: 7 inches means that the photo is 2.54x7=17.78cm long. The 7-inch photo has a scale of 5X7 and a resolution of 124X768.

Extended information:

The size of a photo is in inches, and 1 inch = 2.54cm. Usually, x inch refers to the inch length of the long side of the photo. ID cards, physical examination forms, etc. are mostly 22×32mm smaller than one inch, and the second-generation ID cards are 26 mm× 32 mm..

ordinary one-inch phase is 25mm×35mm. The standard photo size of passport and travel document is 48mm×33mm, the head width is 21 mm ~ 24 mm, and the head length is 28 mm ~ 33 mm).

Reference: Baidu Encyclopedia-Photo Size