See also Data Transfer Usage Calculations, below, for information on calculating or estimating your data transfer needs.

What does "data transfer" mean?

In general, "data transfer" refers to any data transferred into or out of a site. For example, graphics, text, movies, sound files, programs that you or your visitors either download or upload are all considered to be data. Every time a web surfer visits your web pages, data is transferred from our server to their computer. As you want a lot of people to "hit" your site, you want a plenty of data to be transferred! 

Does data transfer include my e-mail messages? 

No. Although e-mail is a type of data transfer, ITS does not include e-mail usage in calculating your hosting plan's data transfer totals. 

Are the files that I upload or download using either FTP or HTTP subject to the data transfer limits? 

Using FTP with your account and password is not part of data transfer limits. However, anonymous FTP (a type of FTP access that lets users login to another computer without using an account) is subject to the data transfer limits. Also, transferring files from your site with HTTP adds to your data transfer totals. 

How can I monitor my data transfer usage?

You can use our on-line statistics monitoring to stay up-to-date on your data transfer totals. To view the statistics for your account, use the View Stats or the Log Files options in your Control Panel. For more information about our statistics packages, please visit our Usage Statistics page.

What are the odds that I could exceed my data transfer limits?

The odds are small. In general, only 1 to 2 percent of our customers tend to exceed the limits. Certain types of web sites, however, may have very high data transfer rates. For example, music sites and entertainment sites often consume large amounts bandwidth. This can lead to high data transfer rates. 

What happens if I exceed my data transfer limits?

As usage reflects the number of people visiting your site ("hits"), exceeding the limit would actually be good for you. If you believe that exceeding the limit was a "one time only" event, you can simply pay for the overage, the additional data transfer amount. However, if  you think that your site could routinely exceed your current plan's data transfer limits, you may want to consider upgrading to a hosting plan that offers higher limits. For detailed information on your options should your site exceed its monthly data transfer limit, please read our Policy on Upgrading a Hosting Account Involving an Overage.

What happens if my business grows or if I think a lot of people will be visiting my site?

Upgrade your plan. It is very important to let us know whether you expect a large number of visitors to your site. For example, if your site was featured on one of the popular morning television shows, you could expect a dramatic increase in visitations. The same would apply if you add a banner ad on a major site such as Yahoo! or AOL. Likewise, popular sites that send flowers can expect heavy usage on Mother's Day and Valentine's Day. To avoid any interruptions of your service, please provide us with advanced notice of any days on which you expect very high web site traffic. We can then plan for that traffic accordingly. 

Why are there data transfer limits at all?

Some web hosting companies say they do not have limits. We use limits to protect those customers who use our shared hosting environments. In such an environment, different web sites located on the same server share system resources. If one site on the server uses too many resources, access to the other sites that reside on the server could be adversely effected. Portioning each site's resources assures that, if one site uses too many resources, the other sites in that shared environment will not experience any significant reduction in performance.

Think of it this way: imagine that you are at a large conference and, during a break, you want to make a quick phone call. However, you misplaced your cell phone. So, you decide to call from the lobby as it has several public phones. As this is a major conference, many of the attendees also choose to make calls during the break. What are your chances of getting an available phone? Well, if unlimited use of the phones is allowed, your odds are not good. However, if the conference coordinator asks each attendee to limit his or her phone time to, say, no more than five minutes, your odds of soon being able to find an available phone rises considerably. So, in that "shared phone environment," placing time limits on individual phone users allows more users to make calls. This same logic applies to placing limits on computing resources in a shared hosting environment. By placing limits on those shared resources, no particular site can use so many resources that other sites cannot function properly.

Theoretically, there are always limitations on the resources that are available for use. If you need more resources for your shared account, you can upgrade your account to one that has higher resource limits. If you expect a consistent and very high number of site visitors, you can elect to circumvent a shared environment altogether by having your own dedicated server account. Such an account provides you with all the system resources on a specific server. 

I don't want to buy more than I need, but I don't want to be hindered either. How do I calculate my expected data transfer usage so that I can choose which plan is best for me? 

Web sites differ greatly in terms of content, file size, number of pages, number of visitors, and so on. To help you to estimate your monthly data transfer usage, we provide some example calculations in the following section called Data Transfer Usage Calculation. In addition, you can always use the statistics options in Control Panel to assist you with your estimates. 

Data Transfer Usage Calculations

Practical Information

Before starting your data transfer calculations, you may need a basic understanding of some typical file sizes and how they relate to data transfer usage. The smaller the total size of a web page, the quicker it downloads. Thus, many web pages are often less than 30 KB in size. A typical graphic file (say, a .GIF file) is about 20 KB to 30 KB in size. However, graphics on web pages are usually smaller, often no more than 15 KB to 20 KB of total graphics size per page. Sometimes web graphic files may be considerably larger than 20 KB. However, for most web sites, using individual graphics files larger than  around 30 KB is not advised. Thus, to speed the loading of your web pages, reducing the size of your web page graphics is essential. You can reduce the size of your graphic images by using the image optimizing features of many popular graphics editing programs. 

One megabyte (1 MB) is roughly 180,000 words of text -- about the size of a typical novel. An easy way to calculate file size is by using multiples of 1000. Calculations based on multiples of 1000 are somewhat easier than those that use the binary method, a method based on multiples of 1024. However, there are still many calculations that are performed using binary units of measurement.

The easy way:

There are 1000 bytes per kilobyte (KB).

There are 1000 kilobytes per megabyte (MB) or 1,000,000 bytes.

There are 1000 megabytes per gigabyte (GB) or 1,000,000,000 bytes per gigabyte.

The binary way:

There are 1024 bytes per kilobyte.

There are 1024 kilobytes per megabyte or 1,048,576 bytes.

There are 1024 megabytes per gigabyte or 1,073,741,824 bytes per gigabyte.

The equivalences shown above will prove helpful in understanding the calculations in the following section, Example Calculations Using the Binary Way.

Example Calculations Using the Binary Way

Estimating  the Number of Files You Can Transfer Per Month

Typically, data usage is measured in bytes. The most common measures are: kilobytes, megabytes, gigabytes, and terabytes. If you have an account that allows up to 2 GB of data transfer per month and your average file size is 10 KB, then you can move 209,715 files per month. Here are the steps that we used to arrive at that answer:

  1. Convert your average file size from kilobytes to bytes by multiplying the average file size (10 KB) by 1024 (the byte equivalent of 1 KB):
10 * 1024 = 10,240 bytes
  1. Determine the number of bytes in 2 GB by multiplying the number of bytes found in one gigabyte (1,073,741,824) by 2:
1,073,741,824 * 2 = 2,147,483,648 bytes
  1. Finally, divide the number of bytes in 2 GB by the average file size in bytes. This provides you with the number of 10 KB files that your account can transfer per month:
2,147,483,648 / 10,240 = 209,715 files per month 

As another example, if you have an account that allows up to 5 GB of data transfer per month and your average file size is 100 KB, then you can move 53,558 files per month. Here are the steps that we used to arrive at that answer:

  1. Convert your average file size from kilobytes to bytes by multiplying the average file size (100 KB) by 1024 (the byte equivalent of 1 KB):
100 * 1024 = 100,240 bytes
  1. Determine the number of bytes in 5 GB by multiplying the number of bytes found in one gigabyte (1,073,741,824) by 5:
1,073,741,824 * 5 = 5,368,709,120 bytes
  1. Finally, divide the number of bytes in 5 GB by the average file size in bytes. This will provide you with the number of 100 KB files that your account can transfer per month:
5,368,709,120 / 100,240 = 53,558 files per month

Estimating the Total Amount of Data Transferred Per Month

Sometimes, you may find it more useful to calculate the total amount of data that is transferred per month instead of the number of individual files transferred per month. For instance, if you use a hosting plan that allows 5 GB of data transfer per month, you may want to estimate how close your site will come to that limit. If you are transferring from another hosting company to ours, you probably already have a good estimate of your average monthly total data transfer. In that case, you probably will not need to perform the following calculation. However, if you are starting a new site, you will need to take educated guesses regarding the values that you need to enter into the equation mentioned below. 

Realize that the following equation applies to sites that are mostly informational. Those sites do not offer many downloadable files. To estimate the total amount of data your site may transfer per month, you would need to perform the following calculation:

(Estimated # of visitors per month) * (Average web page size) * (Average # of pages viewed per visit) = Data Transfer Total per Month

For example, let's say that you expect your site to attract an average of 10,000 visitors per month. Further, your average web page size is about 35 KB. You also expect that visitors will view an average of 5 pages on your site each time they visit. You calculation would be:

10,000 * 35 * 5 = 1,750,000 KB

So, your estimated monthly data transfer total is 1,750,000 KB -- or about 1.75 GB. This is well below your 5 GB limit.

Using Our On-line Web Statistics to Better Estimate Your Data Transfer Usage

If your site is very large or if it has numerous files for visitors to download, you could still exceed your monthly data transfer limit. Trying to estimate the monthly data transfer totals for such a site is, at best, problematic. If your site provides large or numerous files for download -- for example, MP3 files, Windows wallpaper files, graphic files and so on -- you may first want to contact our Sales team. Ask them for their expertise in recommending a plan that fits both your budget and your site type (e-business, music download, etc.). Then, using the Control Panel that we provide with your account, you can monitor the total amount data transferred during the first weeks of your site's operation. The Control Panel's extensive statistical information allows you to determine if your site will exceed its monthly data transfer limit. If it appears that this will be the case, you can call us to upgrade your hosting plan accordingly. 

Additional Information

Measurement units: Even today, there is still a some confusion about what kilobyte, megabyte, gigabyte, etc. actually  mean. Traditionally, the terms kilobyte, megabyte and gigabyte were used to express the binary multiples of 1024, 1,048,576 and 1,073,741,824 bytes:

However, as people often think in decimal terms rather than in binary terms, in December 1998, the International Electrotechnical Commission (IEC: approved a new standard for names and symbols for use in the fields of data processing and data transmission. The standard was adopted in January 1999 by the Institute of Electrical and Electronics Engineers (IEEE: Thus, kilobyte, megabyte and gigabyte should now be used to express the decimal multiples of 1000, 1,000,000 and 1,000,000,000 bytes. A trio of new terms -- kibibyte, mebibyte and gibibyte -- are now used to express the binary multiples of 1024, 1,048,576 and 1,073,741,824 bytes. 

Quote and acknowledgment to the authors, Fred Riley, University of Hull and Graham Davies, Thames Valley University, of the following site:

Please note: the information on this page applies to ITS web hosting plans. It may or may not apply to other environments. If you are looking for a feature described here, or better support from your hosting provider, please consider hosting your site with ITS!

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Naperville, IL 60563
phone 630.420.2550
fax 630.420.2771