 <p>I would think that the proper answer to this, given that you don't want the hardware load measure (CPU, memory, IO utilization), is that heavy load is the amount of requests per time unit at or over the required maximum amount of requests per time unit. </p> <p>The required maximum amount of requests is what has been defined with the customer or with whomever is in charge of the overall architecture.</p> <p>Say X is that required maximum load for the application. I think something like this would approximate the answer:</p> <pre> 0 &lt; Light Load &lt; X/2 &lt; Regular Load &lt; 2X/3 &lt; High Load &lt; X &lt;= Heavy Load </pre> <p>The thing with a single number out of thin air is that it has no relation whatsoever with your application. And what heavy load is is totally, absolutely, ineludibly tied to what the application is supposed to do.</p> <p>Although 200 requests per second is a load that would keep small webservers busy (~12000 a minute).</p>