If you're storing them as strings rather than bit patterns:
IPv4 addresses consist of four 3-digit decimal characters with three . separators, so that only takes 15 characters such as 255.255.255.255.
IPv6 addresses consist of eight 4-digit hex characters with seven : separators, so that takes 39 characters such as 0123:4567:89ab:cdef:0123:4567:89ab:cdef.