In some versions of Windows, the usual method of viewing a file–double clicking on it–doesn’t work for BLG files. If you can’t view a BLG file just by double clicking on it, here’s the other way to open a BLG file in Windows.

This works in current versions of Windows and all the way back to Windows 2000.

open a blg file in Windows

BLG is the Performance Monitor file format. Here’s how to open one if double-clicking doesn’t work.

BLG is the file format that Performance Monitor, sometimes called Perfmon, uses to save performance data. Most newer versions of Windows make it easy. Double-clicking on the BLG file makes it open, as you would expect any other filetype to work. But if it doesn’t work for some reason, or you’re working with a really old Windows box, here’s how to get the file open to you can view and analyze it.

Launch Performance Monitor to open a blg file

On really old versions of Windows like Windows 2000, Windows XP and Server 2003, go to Control Panel > Administrative Tools. Open Performance. On recent versions of Windows you can just click Start and start typing Performance, and pick Performance Monitor from the list when it comes up.

How to open a BLG file from inside Performance Monitor

The icon you want varies in position and appearance on the toolbar. It’s usually kind of square and it’s usually on the far left or the far right. Hover over each icon and look at the tooltips. You want the one that gives the tooltip of “View Log File Data.” Translated into the English you and I speak, that means, “Open a stinkin’ BLG file!” You can also try hitting CTRL-L. In recent versions of Windows, that keyboard shortcut works.

Click that icon. Then on the resulting dialog box, click the source tab, click the button labeled Add. Change the radio button to Log Files, and you’re on your way. Click OK, and Performance Monitor will render the data in the BLG file so you can work with it.