If the account has a maximum of 20Gb per 31 day month then: 20Gb == 20,000 Mb == 20,000,000 Kb In every 31 days there are: 2,678,400 Seconds == 31 days * 24 hours * 60 minutes * 60 seconds So your Kb/s limit should be set to: 20,000,000 Kb / 2,678,400 s = 7.461 Kb/s
Actually, that's KB/s - bytes. In Kb/s (bits), it's 61kbps. Just being picky.
Note: While this restricts the total bandwidth usage per month, it does also prevent the account from ever serving more than 7.461 kb/s You should check the usage patterns, as you'll probably find that at certain points it exceeds this, and other times it doesn't...
This is is a very important point. If you actually restrict your user to 7.5kB/s, he'll likely scream bloody murder. You'd be well served to search on mod_throttle where you can actually limit traffic by GB served in the month.
Good luck, Brandon _________________________________________________________________Join the world?s largest e-mail service with MSN Hotmail. http://www.hotmail.com