Common sizes are

3 inches 8.9 * 6.4 cm

4 inches 10.2 * 7.6cm

5 inches 12.7*8.9cm

5 inches 12.7 * 9.52cm.

6 inches15.2 *10.2cm.

6 inches15.2 *11.4cm.

7 inches12.7 *17.8cm.

8 inches 15.2*20.3cm

9 inches 15.2*22.8cm

A six-inch photo is usually15.2cm×10.2cm..

There is another saying that it is six inches, and its size is15.2cm×11.4cm..

Different pictures have different sizes because of different cutting sizes. Generally speaking, the size is in feet, 1 foot = 2.54cm = 25.4mm. People in China often use inches to indicate the size of photos, but their habits are different. The commonly used photos are 7-inch and 8-inch, and the photos can also be scaled according to the size, as long as the pixels can meet the requirements. For a 6-inch picture, it is the first choice for printing because it is suitable in size and convenient to carry.