No one operates at full capacity 24 hours a day, if you do, your website doesn't matter much as it will be unusable during peak hours.
Based on over a hundred gbps of aggregated adult traffic, you will see roughly 200GB per Mbit of "real world" usage. Depending on your traffic, this can go up or down - but usually it will stay within the 170GB - 220GB range.
So, 2000GB is a good rough estimate real-world, if your traffic patterns are "average" for the industry.
Hope the info helps!
-Phil
|