What is the maximum permittable size in bits for an IPv4 packet?

The maximum permissible size for an IPv4 packet is 65,535 bytes, which includes both the header and the data payload. Since the maximum size of the header is 60 bytes, this allows for a maximum data payload of 65,475 bytes. However, in practical use, the Maximum Transmission Unit (MTU) often limits the size of packets on networks, typically to 1,500 bytes for Ethernet.