Site Hosting Bandwidth Requirements

Site Hosting Bandwidth Requirements

Postby apex » Mon Feb 09, 2009 12:37 am

*REPOSTED* Feb, 2009. Original post from 2005.

When looking for a hosting provider you'll notice the amount of bandwidth differs greatly between hosts and plans. It's also hard to know how much bandwidth you actually will need. This primer is meant to help you determine how much bandwidth you might use based on real world experiences and examples.

Before we consider the amount of bandwidth you need, you should understand the different types of bandwidth measurements used by hosting companies. Bandwidth is defined as the total transmission capacity* of a given network connection.


Dial-up modem: 56Kbps
ISDN: 128Kbps
T-1: 1.54Mbps*
Ethernet: 10Mbps
Fast Ethernet: 100Mbps
Gigabit Ethernet: 1000Mbps

*Note: 1Mbps = 1024Kbps
*Ethernet, Fast Ethernet, and Gigabit Ethernet connections are "Full Duplex". This means they can send AND receive data at the listed speed simultaneously. So in reality you could transfer 20Mbps of data using a 10Mbps internet connection if you were sending and receiving at full capacity.

Most providers offer plans that are not limited by their bandwidth, but in the actual amount of data transferred in a given month. To make it very confusing they also call this number bandwidth. The difference is, one is the burstable capacity and the other is the actual amount of data transferred in a given month. Unless you are paying for Unmetered bandwidth, you need to know the differences between the two.

A common plan would include a 10Mbps internet connection with 1000GB's of monthly data transfer. This means you can transfer data at speeds of up to 10Mbps, but not all the time. If you used the entire 10Mbps (10Mbps output and 10Mbps input) you would transfer about 6412GB's by the end of the month. That's well more than your 1000GB/month allotment. An unmetered connection means a connection of a certain speed of which you can use all or none of the capacity, you can't 'go over' your allotted amount. The good thing about a burstable connection is you get the advantage of being able to send data at high speeds if you need to, but if you don't use that high speed all the time, you don't have to pay for it.

You should be careful of 'overage' fees assessed by providers. If you transfer more data than you were allotted in a month you can be charged two to ten times (or more) your normal rate for the bandwidth that was over your allotted amount. This is one way hosts protect themselves from clients who use more bandwidth than they expected (see Overselling) and also how they might be giving you a bill for hundreds or thousands of dollars of overage fees when your entire monthly cost, before going over your limit, was less than $100. You should monitor your usage throughout the month in order to prevent possible overage charges.

Providers use three different methods of measuring and charging for monthly bandwidth usage.

1) Average Kilobits per second (Kbps)
2) Total GigaBytes per month (GB/mo)
3) 95th Percentile

The first two methods equate to the same thing. Kbps is the average bandwidth utilization each second. If you know the monthly average you can convert it to the monthly total (GB/mo). Using a little math you can convert one term to the other.

To convert:

Monthly average Kbps * 60 * 60 * 24 * 30.4 / 1024 / 1024 / 8 = GB/mo
GB/mo * 8 * 1024 * 1024 / 30.4 / 24 / 60 / 60 = Monthly average Kbps

This formula does three things. It accounts for the number of seconds in a month in order to convert the average speed per second to the total amount transferred in a month. It converts Kilobits to Gigabits and finally, It converts bits to bytes (there are 8 bits in a byte).

Some hosts use the third method, 95th percentile billing. It's like monthly average Kbps but without going into specifics, you will usually pay slightly more for the same amount of bandwidth than you would when using either of the above mentioned methods.

Here are some real world examples:

Online Library/Museum
10,000 Unique Visits/day. (200,000 hits)
Main page: 50KB
90GB/mo (292Kbps avg.)

Medium Association Site
5,000 Unique Visits/day. (80,000 hits)
Main page: 30KB
40GB/mo (130Kbps avg.)

Medium Weblog Site
10,000 Unique Visits/day. (100,000 hits)
Main page: 66KB
25GB/mo (82Kbps avg.)

Small Text based Site (few pictures):
400 Unique Visitors/day. (4000 hits)
Main Page: 10KB

Small Site (many pictures):
200 Unique Visitors/day. (2000 hits)
Main Page: 25KB

Small Download Site (200 small files):
600 Unique Visitors/day. (7,000 hits)
Main Page: 15KB

Software Company Site (3 medium programs):
2000 Unique Visitors/day. (30,000 hits)
Main Page: 50KB

The average usage for these seven sites is 31GBs/month each. These numbers will fluctuate monthly for each site and a large number of sites will end up using little or no bandwidth. Keep in mind this only accounts for web-based traffic. Backups, file transfers, ssh connections, mail, etc. will add about 10-25% more to your monthly usage. Streaming media could easily double or triple these numbers, as would hosting files >10MB in size, VoIP, and the like.
Posts: 355
Joined: Sun Aug 05, 2001 7:00 pm

Return to Legacy Hosting Discussion

Who is online

Users browsing this forum: No registered users and 1 guest