This is just the raw physical bits that can be transfered. You then have to take into account the overhead from ethernet headers (18 bytes per frame), the interframe gap (variable depending on your interface speed), IP headers (20 bytes, plus optional headers), and TCP headers (20 bytes, plus possible optional headers).
These numbers also assume you are using 100% of the capacity of the line for the whole month. In reality, if you're doing that, your users are probably getting packet loss and poor performance. Normal web traffic, if you look at it on a graph, looks like a wave with peaks and valleys. If your traffic distribution is such that the graph peaks at 1Mbps, then you're probably getting about 180GB-200GB of data transfer out of that 1Mbps.
As a general rule for web traffic, count on getting about 200GB of usage out of each 1Mbps. Depending on your specific circumstances, it may be a little less or a little more.
It depends on how you're using it - if you're pushing a constant 1 Mbps stream, you'll use about 320 GB in a month. If you have variable traffic that isn't always 1 Mbps, you'll use less - I believe the 190 figure is based on what a pool of sample customers actually used throughout a month.
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Listen to the 180-200 crowd. Scott's answer (bqinternet) is right on the money. (SHOUT OUT - started using your service for a couple of customers this month, so far no problems - great value).
For you guys that continue to insist that 320GB is a practical answer, why not go ahead and say 640GB, after all it is a two-way pipe
Originally Posted by rlanham
So then 190 wouldn't actually be 1Mbps, you would be using less then that, correct?
Nope, it's still 1mbps. In the real world, there's no direct correlation between instantaneous transfer RATE (1mbps) and aggregate data transfer over a period of time (GB). You can literally have a port at 1mbps/95th percentile that transferred 160GB in a month, and another that also billed 1mbps/95th percentile that transferred 260GB. Two ports, both 1mpbs billed usage, very different amounts of data transferred.
It's IMPOSSIBLE to know how much data you've transfered based solely on your 95th percentile billing, which is why many clueful participants in this forum suggest the 180-200GB value, which is a reasonable, realistic expectation.
Last edited by cbtrussell; 04-01-2008 at 01:57 PM.
I remember I saw this on a host's website and 1Mbps is equivalent to about 330GB of bandwidth.
Assuming the full 1 Mbps is sustained 24x7x30, that's about right, give or take a few GB.
What nobody has mentioned, however is this. Real-life traffic patterns are not flat lines. Utilization goes up during peak hours, then falls off at non-peak.
If you're actually flat-lining your connection 24x7, your visitors are going to be miserable. Expect very slow browsing, terrible response times, packet loss, and in general an audience that is not in a hurry to return to your basically-unuseable site, all because the pipe is too congested to be useful.
You need to provision with your peak traffic levels in mind-- not how many GB you can shove across the wire in 30 days.