Print Size Chart

Standard photo sizes: 
5"x7" (12.7 x 17.78 cm) 
8"x10" (20.32 x 25.4 cm) 
11"x14" (27.94 x 35.56 cm)
16"x20"(40.64 x 50.8 cm)
20"x24" (50.8 x 60.96 cm)
24"x36" (60.96 x 91.44 cm)

ISO* print sizes:
A5 (14.8 x 21 cm) 
A4 (21 x 29.7 cm) 
A3 (29.7 x 42 cm)
A2 (42 x 59.4 cm)
A1 (59.4 x 84.1 cm)

Additional common sizes:
4"x6" (10.16 x 15.24 cm) 
6"x8" (15.24 x 20.32 cm) 
8.5"x11" (21.59 x 27.94 cm) 
8"x12" (20.32 x 30.48 cm) 
9"x12" (22.86 x 30.48 cm)
10"x15 (25.4 x 38.1 cm)
12"x12" (30.48 x 30.48 cm) 
12"x16" (30.48 x 40.64 cm) 
12"x18" (30.48 x 45.72 cm) 
16"x16" (40.64 x 40.64 cm) 
18"x24" (45.72 x 60.96 cm)
20"x20" (50.8 x 50.8 cm)
20"x28" (50.8 x 71.12 cm)
20"x30" (50.8 x 76.2 cm)
* ISO = International Standard Organization
These are common paper sizes in Europe, Australia, New Zealand.