Raspberry Pi
The Raspberry Pi comes in three different sizes. The 'standard' size is used for all Model B versions, and is 85.6 mm x 56.5 mm (3.370 in × 2.224 in). The 'compact' size is used for all Model A versions, and is 65 mm × 56.5 mm (2.56 in × 2.22 in). The 'zero' size is used for all Raspberry Pi Zero versions, and is 65 mm × 30 mm (2.56 in × 1.18 in).