How to monitor memory usage in Windows using Performance Monitor

A high memory total alone does not show whether Windows is running short of usable RAM. Performance Monitor tracks memory usage over time, separating available physical memory from committed virtual memory.

Committed memory needs backing from RAM or page files, so its utilization percentage is different from the percentage of physical RAM in use. Reading it alongside available memory helps distinguish growing memory demand from an isolated busy moment.

The live view suits a slowdown that is happening now, while a Data Collector Set saves readings for later inspection. Recording continues until stopped and consumes disk space; creating and starting a collector may require administrator permission.

1. Press Win + R to open the Run dialog.
2. Enter perfmon in the Open field.
3. Press Enter to launch Performance Monitor.
4. Select Performance Monitor under Monitoring Tools.
5. Click the green Add Counters button on the toolbar.
6. Expand Memory in the Available counters list.

   The computer selector stays at <Local computer> for readings from this PC.

7. Select Available MBytes and % Committed Bytes In Use using Ctrl for the multiple selection.

   Available MBytes measures physical memory available for use, including reusable standby memory. % Committed Bytes In Use measures committed memory against the commit limit; a value near 100% means little commit capacity remains.

8. Click Add » to include the selected counters.
9. Click OK to return to the live view.
10. Remove the selected default % Processor Time counter with the red Delete toolbar button.
11. Open the graph-type dropdown beside the chart icon.
12. Choose Report to display the counter values in their own units.

    The line graph shares one vertical axis, which can hide an unscaled megabyte counter above its maximum.

13. Confirm that both Memory readings update over time.

    Sustained low available memory alongside high commit utilization warrants investigation; short spikes during app launches or updates do not establish a memory shortage. Live monitoring is complete here; the remaining steps record readings for later review.

14. Choose New → Data Collector Set from the Performance Monitor node's right-click menu.

    This route copies the counters already in the live view.

15. Name the data collector set MemoryUsage.
16. Click Next to continue from the name page.
17. Click Next to keep the default log directory.

    The default location is C:\PerfLogs\Admin\MemoryUsage when Windows is installed on drive C.

18. Click Finish to save the data collector set.

    The default Run as account and Save and close option need no changes.

    If the console closes after saving, reopen perfmon from Run.

19. Open Data Collector Sets → User Defined → MemoryUsage.

    The recording keeps writing to disk until stopped; a short capture around the slowdown is usually easier to inspect than an unattended log.

20. Click the green Start toolbar button to begin recording.
21. Click the square Stop toolbar button after the capture period.

    A brief trial needs several samples; a capture of about 30 seconds is enough to check that logging works.

22. Choose Latest Report from the MemoryUsage set's right-click menu.
23. Select Available MBytes in the recorded graph's legend.
24. Confirm that the report contains the captured time range and memory values.

    Average, Minimum, and Maximum show the selected counter's recorded values. The legend's Scale changes its plotted height, so a line at 18 with a scale of 0.01 represents about 1,800 MBytes rather than 18 MBytes.