to Calculate and Speed-Up the Download
Time of Your Web Site
2002 Herman Drost
Have you ever experienced the
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
many visitors. This means that the web designer must use
images sparingly and choose file formats carefully.
How to Calculate Download Time
1. Check the size of the HTML file and any associated
images, files or programs. You can do this by right clicking
on the 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
2. Determine the speed of your network connection. Some of
the 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
1.544 Mbps (million bits per second) - full T1,
enterprise grade network line (equivalent of 24 phone
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 the
file size to bits, you should first convert it to bytes (84
kilobytes = 84,000 bytes). Then convert the bytes to bits by
multiplying 84,000 by 8 (1 byte = 8 bits), which results in
|4. Divide the
file size (672,000 bits) by the connection speed (56,000
bits per second). The bits cancel out, and the results is
12 seconds. This is the amount of time it will
theoretically take to download the Web page.
Remember that the figure derived from these four steps, is
a theoretical measurement. It does not consider certain
factors, such as the 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 the 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 the Download Time of Your Site
1. Optimizing Images - this refers to the 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 the 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 the site loads. You need
to seek the perfect balance between size and quality.
2. File Formats - There are two main types of
images on the Web:
GIF (Graphics Interchange Format) and JPEG (Joint
Photographic Experts Group) files. Each format compresses
files differently and each exhibits different strengths
The GIF standard works better for images with large areas
of similar, flat colors, such as logos, drawings and
JPEG is better at compressing photos and images with
complex and widely variable colorings. Within each
standard, you can adjust quality settings. Those
adjustments will affect file size and image appearance.
The key to optimization is to try out all the different
options to achieve the smallest possible file size while
maintaining an acceptable level of quality.
3. Reuse Your Images - increase the efficiency of
your site by making intelligent use of the fact that
browsers usually cache (save for later use on the user's
hard drive) downloaded files, including Web site images.
Therefore, when a page calls for an
image that's already been used, it loads and displays much
more quickly on subsequent page views because it is coming
from a local hard drive rather than the Internet.
Therefore, one of the wisest things you can do is to reuse
images; whenever possible, use the same logo on multiple
pages, the same graphic buttons and the same graphic
dividers. After the first time a user loads these
elements, they'll pop up very quickly on subsequent pages.
4. Text - text on pages loads far more quickly than
images, permitting you to convey more information more
efficiently. Don't have a page on your site that makes the
user scroll down several times. Too much text on one page
will slow the download
time of your site. It will also make it very tiring for
your visitor to read all your text.
5. Web Site Enhancements - there are hundreds of
other elements you can choose to include on your site.
This may include such things as: search boxes, pull down
menus, opinion polls, hit counters, rotating banner ads,
associate programs etc. You can have a multitude of
options to add virtually unlimited functionality (and
clutter) to your web site.
To sort out if you need any of these extras, ask yourself
How does it help me accomplish the purpose of this web
If you can't think of a good answer, chances are you don't
need the extra element. Make sure they fit into your
site's overall aesthetics. Check how they affect load
By reducing the download time of your web site, visitors
will return because they remembered how fast it was to
find what they wanted (rather than the slower site of your
competitors). This may ultimately increase the number of
Herman Drost is a Certified
Internet Webmaster (CIW) owner and
author of iSiteBuild.com
Low Cost Hosting and Site Design
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