Written by Herman Drost

Have you ever experienced frustration of waiting for a web site to download, then giving up and moving on to another? This is because most web users lose their attention after 10 seconds. If your site takes longer than this to load, you will be losing many visitors. This means that web designer must use images sparingly and choose file formats carefully.

How to Calculate Download Time 1. Check size of HTML file and any associated images, files or programs. You can do this by right clicking on file or image and reading its properties. For example, you may have a page that consists of 10 files, for a total of 84 kilobytes (KB). For a more extensive explanation for calculating file sizes, see my previous article - "How Much Hosting Space Do You Need?" (www.isitebuild.com/hostingspace.htm).

2. Determine speed of your network connection. Some of more common speeds are: 14.4 Kbps (kilobits per second) - slow modem speed 28.8 Kbps - typical modem speed for some users. 56 Kbps - typical modem speed for most users with a dial-up connection. 1.544 Mbps (million bits per second) - full T1, enterprise grade network line (equivalent of 24 phone circuits).

3. For this example, we will use 56 kilobits per second (Kbps). The connection speed and file size must be converted to a common unit of measure for division: either bytes or bits. Remember that 1 byte equals 8 bits. The connection speed is already defined in bits: 56 kilobits = 56,000 bits. To convert file size to bits, you should first convert it to bytes (84 kilobytes = 84,000 bytes). Then convert bytes to bits by multiplying 84,000 by 8 (1 byte = 8 bits), which results in 672,000 bits.

Divide file size (672,000 bits) by connection speed (56,000 bits per second). The bits cancel out, and results is 12 seconds. This is amount of time it will theoretically take to download Web page.

Remember that figure derived from these four steps, is a theoretical measurement. It does not consider certain factors, such as fact that 56 Kbps modems rarely operate above 50 Kbps. Nor does it consider network overhead, such as noisy phone lines, or network congestion.

Therefore best way to determine how quickly users can download your web sites pages, is to test them in a real-world setting. For example, test your web site by accessing it through a dial-up (i.e., telephone) connection. That method will give you a much more reliable estimate.

Factors that Affect Download Time of Your Site 1. Optimizing Images - this refers to process of striking a balance between file size and image quality. Your images should not be too large or have too many on your web site. This will cause your pages too long to come up in users browser and they'll lose their patience.

Of course, if you images are too poor (too small, or with too low of a resolution), your site will be unattractive and it won't matter how quickly site loads. You need to seek perfect balance between size and quality.