Bandwidth calculations and how web hosting companies estimate them

Estimating Bandwidth

Web hosting companies calculate your bandwidth usage by using one of three different methods.

  • Per use
  • capped
  • 95% use

Each method is quite different so make sure you understand what your needs are with how they compare in your webhosting hosting plans.

So first things first, a bit of a basic grounding; data transfer is measured in bits or bytes where:

8 bits (b) = 1 byte (B)
1024 bytes = 1 kilo byte (KB)
1024 kilo bytes = 1 mega byte (MB)
1024 mega byte = 1 giga byte (GB)

And data transfer is the measure of these bits or bytes being transferred over a period of time. So for example 100 Mbps means 100 mega bytes are being transferred in one second. Saying all that, for all intents and purposes most hosting companies designate 1 month as the period of time; so If your hosting plan states that you have 50 GB of bandwidth, that you can transfer as much as 50 GB of data in one month as part of the package before incurring additional charges, etc. etc.

To calculate usage, your host relies on usage reports (Multi Router Traffic Grapher (MRTG) is one example) that show your web site’s average incoming and outgoing traffic, once that is ascertained, the following formula is then applied:

( Monthly Average incoming + Monthly average outgoing data ) /8 x 60 sec x 60 min x 24 hrs x 30.5 days = Total month’s bandwidth

Per Use Method

Under the per use method of bandwidth calculation, the web hosting company calculates your usage in a month and invoices you the price per Gigabyte, Megabyte or Kilobytes. Most hosting providers, then charge in predetermined blocks that may or may not vary per package (e.g. blocks of 10 GB etc. etc.) so that if you exceed your usage, they would charge you an additional amount for the incremental block of bandwidth used.

Capped Method

Under the capped method of bandwidth calculation, your web hosting provider will allocate a certain amount of predetermined bandwidth per month. If you exceed this bandwidth usage your web site will either become inaccessible or is considerably delayed. While this sounds like a bad option, most hosting providers use this method because it’s a fixed cost, and easiest to determine. If your hosting provider uses this methodology you should pre decide a plan with more bandwidth than you expect to use and monitor it to make sure that you will not exceed it.

95% Method

Under the 95% method of bandwidth calculation hosting provider looks at your total bandwidth usage for the month, it then discards the top 5% of use. The remaining 95% of transferred data will be used to calculate your usage. So if your site exhibits occasional usage spikes, this might be a good method for you as the peaks will not be included in your bandwidth usage calculations.

Knowing this, you should check your web host’s control panel to determine your average usage. Then we suggested you add on a certain percent for growth you expect or can determine from your historic usage patterns and then make sure that you use a plan that matches your site’s bandwidth needs.

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