The size of the photo is indicated by the long side. 1 inch equals 2.54 cm, and so on, 2 inches equals 5.08 cm, 3 inches equals 7.62 cm ... 40 inches equals 10 1.6 cm. After all, the size of a photo doesn't need to be accurate to millimeters. Especially, the larger the photo size, the greater the absolute error value of its accuracy under the condition of constant relative percentage error. From the practical needs, we usually take approximate integer values, which is also an example of the application of fuzzy mathematics concepts in life. So the photo size of each size can't be exactly the same as arithmetic.

The size of the photo is in inches, 1 inch =2.54cm, and usually x inches refers to the inch length of the long side of the photo. For example, 5 inches means that the photo width is 2.54x5 =12.7cm; 12 inch means that the width of the photo is 2.54x12 = 30.5cm. ..

ID card, physical examination form, etc. Most of them are 32×22mm small, 26mm×32mm second-generation ID cards and 25mm×35mm ordinary one-inch photos. The standard photo size of passports and travel documents is 48mm×33mm, the head width is 2 1 mm ~ 24 mm, and the head length is 28 mm ~ 33 mm).