How do you estimate the size of a photo file path is 256 bytes?

PhotoPath (256 bytes), I don’t understand how does this number came out?

The default character path length limitation (MAX_PATH) used in Paths, Namespaces, and Naming File is 256 bytes. This is also because there are 256 ASCII characters and each ASCII character is equal to 8 bits, which is the equivalent of 1 byte.