Historically, measuring the amount of memory in use by a Windows system has been a somewhat confusing endeavor.  The labels on various readouts in Task Manager, among other places, were often either poorly named or simply misunderstood .  I’ll tackle a prime example of this, the “commit” indicator, later in this post.  But first, let’s look at a simple way to measure the amount of physical memory in use on your system. In Windows 7, the folks building the Task Manager performance tab tried to make it a little easier to understand the usage of physical memory on your system.  The most interesting bits are here: What do these values tell us? - We are looking at a machine with 4GB of physical memory installed. - 71% of that physical memory is currently in use by applications and the system.

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Measuring memory usage in Windows 7