What Is “Defragging,” and Do I Need to Do It in Windows 10?

Dear Vince,
I hear people talk about “defragging” their computers all the time as a way to make it faster, but I’m not really sure what that means. What does defragging do and is it something I need to do to my computer? How often? Confused Customer

“Defrag” is short for “defragment,” which is a maintenance task required by your hard drives.

Most hard drives have spinning platters, with data stored in different places around that platter. When your computer writes data to your drive, it does so in “blocks” that are ordered sequentially from one side of the drive’s platter to the other. Fragmentation happens when those files get split between blocks that are far away from each other. The hard drive then takes longer to read that file because the read head has to “visit” multiple spots on the platter. Defragmentation puts those blocks back in sequential order, so your drive head doesn’t have to run around the entire platter to read a single file.

Over time, files on your hard drive get fragmented, and your desktop or laptop slows down because it has to check multiple places on your drive for those pieces.

Windows 10, like Windows 8 and Windows 7 before it, automatically defragments files for you on a schedule (by default, once a week). However, it doesn’t always run consistently, so if you notice files are taking longer to load or you just want to double-check every month or so, you can see how fragmented the drive is in Windows.

A note about Solid State Drives (SSD): SSDs work differently than traditional mechanical hard drives. Conventional wisdom is that SSDs don’t need to be defragmented and doing so can also wear down the drive. However, Windows does defragment SSDs once a month if necessary and if you have System Restore enabled. This isn’t something to worry about, though, because the automatic defragmentation is meant to extend your drive’s life and performance.

So with SSDs, just let Windows do its thing and don’t worry about de-fragmentation. You can use the Optimize Drive tool below to do a general optimization of the drive, including sending the TRIM command to optimize performance. This doesn’t do a traditional defrag on the SSD, though. For your mechanical drives, here’s how to defragment your drive in Windows 10.

If You Use a Mac

If you use a Mac, then you probably don’t need to manually defragment, since OS X will do it automatically for you (at least for small files). However, sometimes defragging—particularly if you have a lot of very large files—can help speed up a slow Mac.

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