Sizing of syslog storage

Hello,

We need to implement a syslog containing a trace of all web access of 15 users.

But we don't have any idea of the volume required.

Do you have any estimation (a rough range is enough) of the daily syslog volume for an average web use (webmail + surf) ?

We will only register :

- origin MAC address

- origin IP address

- network port

- destination IP address

- timestamp

Thanks in advance for your help.