Online SHA-512 Hash Generator
The output of the SHA-512 algorithm is a hash of 512 bits in size. The bits are grouped into 4 bit nibbles which can then represent the digits 0-15 which conveniently maps to a hex value displayed as 0-9 and a-f. So the hash generates 512 bits which is 128 hex values (512 / 4 = 128). It would make a 128 characters long digest in hexadecimal.