Wallet print size is usually 2.5 x 3.5 inches for the standard photo wallet size, and some labs also offer mini wallets at 2.5 x 1.75 inches or die-cut wallets at about 2 5/16 x 3 5/16 inches. Standard wallet prints are commonly sold in sheets of 4, 8, or 16, depending on the printer.

Quick size guide

Type| Typical size
---|---
Standard wallet print| 2.5 x 3.5 inches 15
Mini wallet| 2.5 x 1.75 inches 15
Die-cut wallet| 2 5/16 x 3 5/16 inches 15

If you want, I can also help with the pixel size needed for a sharp wallet print.