The Fragment Offset data field is a 13-bit long data field in the IP header that indicates the location of the fragment data in relation to the beginning of the data block. The fragment offset is displayed in eight octets, which corresponds to 64 bits.
For a non-fragmented datagram or for the first fragment, the value of the fragment offset is always set to "0". The fragment offset defines the position of the respective fragment in the datagram as a multiple of 8 bytes. This means that data packets can only be fragmented according to a multiple of 8 bytes. With the 13 bits of the offset field a maximum of 8,192 (2exp13) fragments per datagram can be identified.