The first step in designing a Web site load test is to measure as accurately as possible the current load levels.

Measuring Current Load Levels

The best way to capture the nature of Web site load is to identify and track, [e.g. using a log analyzer] a set of key user session variables that are applicable and relevant to your Web site traffic.

Some of the variables that could be tracked include:

the length of the session (measured in pages)

the duration of the session (measured in minutes and seconds)

the type of pages that were visited during the session (e.g., home page, product information page, credit card information page etc.)

the typical/most popular ‘flow’ or path through the website

the % of ‘browse’ vs. ‘purchase’ sessions

the % type of users (new user vs. returning registered user)

Measure how many people visit the site per week/month or day. Then break down these current traffic patterns into one-hour time slices, and identify the peak-hours (i.e. if you get lots of traffic during lunch time etc.), and the numbers of users during those peak hours. This information can then be used to estimate the number of concurrent users on your site.