title: total registered vs. concurrent users
body: <p>Is there a proper way, equation or technique in general to say, "My web application needs to support <code>N</code> number of total users which via this equation/technique/rockHardExperience tells me that I need to support <code>X</code> number of concurrent page requests"?</p>
  
  <p>From my research and/or gut feeling it seems like it would be something like:</p>
  
  <p><code>totalLoadCapabilityRequired = (totalUsersN x .10 ) * .5</code></p>
  
  <p><code>where .10 is for roughly 10% on at any given time</code></p>
  
  <p><code>and the whole thing multiplied by 50% to suggest a 50% chance of those total users online executing a request at roughly the same time</code></p>
  
  <p>any insights would help me in making sure I implement support in my application that is on par for the demand. I expect a lot of users but don't want to over anticipate too early. I know for starters that the org I am programming for will have 45,000 users that they want to use my system, with an anticipation on success for many more.</p>