This page says the following:
TCP controls this maximum size, known as Maximum Segment Size (MSS), for each TCP connection. For direct-attached networks, TCP computes the MSS by using the MTU size of the network interface and then subtracting the protocol headers to come up with the size of data in the TCP packet. For example, Ethernet with a MTU of 1500 would result in a MSS of 1460 after subtracting 20 bytes for IPv4 header and 20 bytes for TCP header.
Shouldn't the number of bytes of the Ethernet header be subtracted too?