How Often Should You Defrag Your Computer?

Defragging your PC is easy. Knowing when to do it is not.

Optimize Drives
The Optimize Drives program in Windows 10.

I received an email from a reader and thought it could be of value to all readers of this site. She asked: "My defrag window says 3 items: C: and E: backup and system (no letter). Which should I defrag and how often?"

When greeted with so many choices as our reader above many people wonder what the best way forward is to properly defrag their system.

This was my response:

"You want to defragment your C: drive.

If you're a normal computer user (meaning you use it for web browsing, email, games, and the like), a once-per-month defragment should be fine. If you're a heavy user, meaning you use the PC eight hours per day for work, you should do it more often, probably once every two weeks. Anytime your disk is more than 10% fragmented, you should defragment it.

Also, if your computer is running slow, you should consider doing a defrag as the fragmentation may be causing your PC to run more slowly. We have a step-by-step guide for running a defrag operation, and we've also got a guide for defragging in Windows 7."

Note that under Windows VistaWindows 7, Windows 8, and Windows 10 you can schedule your defrag to happen as often as necessary; Windows XP doesn't allow that option as simply as more modern versions of Windows do.

In fact, in Windows 7 and up defragmenting should be scheduled to happen automatically.

You can check inside the defrag desktop program itself to see how and when its scheduled to run and then adjust accordingly.

As you may have guessed by now, defrag is short for "defragment."  It means to put your computer files back in a logical order, which allows your PC to run faster.. Even though you view files as a single unit when you open them, they are actually an amalgam of little segments that the PC puts together on demand.

  Over time, file parts can be scattered all over your hard drive. When that scattering is too widespread it takes much longer for your PC to grab all the right bits and put together your files thereby slowing down your system's responsiveness.

Defrag and SSDs

While defragmenting helps keep a hard drive in tip-top shape it does not help solid state drives (SSDs). The good news if you are running any operating system from Windows 7 and up you don't have to worry about your SSD. The operating system is already smart enough to identify when you have an SSD, and it won't run the traditional defragmenting operation.

In fact, if you look at the defragment application in Windows 8 or 10 you'll see that defragging isn't called defrgagging at all. Instead it's called "optimization" to avoid confusion with old school defragging. Optimization is just what it sounds like: a method your operating system uses to improve the operation of your SSD.  

If you really want to get into the weeds about SSD  maintenance check out a blog post by Microsoft employee Scott Hanselman that explains SSDs and defragging in greater detail. 

SSD optimization is great for anyone using Windows 8 and 10, and Windows 7 users don't have to worry about defrag messing up their drive.

But if you happen to be using an SSD with Windows Vista you'll want to disable automated disk defragmentation if it's enabled.

An even smarter move for Windows Vista users would be to start thinking about moving past the aging operating system. Microsoft plans to end extended support for Windows Vista on April 11, 2017. At that point Vista will no longer receive security updates meaning the operating system will remain unsafe if vulnerabilities are found (and they almost certainly will be).

At that point, Vista's outdated treatment of SSDs will be the least of your worries.

Updated by Ian Paul.