how to get network packet size

how to get network packet size

I would like get network output rate(kb/sec)

I type command "netstat -i"
Ipkts Ierrs Opkts Oerrs 653387 0 678202 0

but i didn't know what is it packet size ,
how could i get it?

netstat -i -I <interface name>

The packet size is in the "Mtu" column.

Beware that these computers can negotiate a different packet size with the router and that the new packet size will not be visible to netstat.