How Often Should I Defrag?

Category: Hard-Drives

I've heard conflicting advice on when and how often to defragment my hard drives. Some say never, while others say weekly or monthly. They can't both be right, can they? What's your advice on defragging a drive?

When Should You Defrag Your Hard Drive?

Actually, they could both be right! By the time you finish reading this, you'll see why. Defragmenting your hard drive's files is one of the most effective ways to boost overall system performance. How often you should defrag depends on several factors.

Files become fragmented in the normal course of reading, writing, expanding, and deleting them. For example, if you add a chapter to your Great American Novel, the file is bigger than it used to be. It may no longer fit between the files where it was stored previously. So the file gets broken up into two or more pieces, which are stored in different locations on the hard drive. The same thing can happen with a large download. Although the file appears as a single chunk of data to you, it may actually be scattered all over the hard drive, in dozens of little pieces.
Defragger screenshot

The problem with fragmentation is that the read-write head of the drive must move around a lot more to read the entire file. This motion takes time and degrades performance. It also wears out the drive faster. Think of it like a printed document, scattered all over your home. It would take a much longer time to find, sort and stack all the pages, than if it was in one neat pile, right?

Defragging stitches fragmented files back together and writes each file to one contiguous section of the hard drive. Defragging also strives to maximize free space so that future files are less likely to be fragmented.

Windows includes a Disk Defragmenter utility that will get the job done. But there are many third-party defraggers that claim to do a better job than Windows. Some popular commercial defraggers include Diskeeper, PerfectDisk, and Auslogics Disk Defrag. But one of my favorites is IOBit's SmartDefrag. It can be set to run in real-time, pausing when you are using the system, so that your system is constantly defragmented. Best of all, it's free!

If you don't want SmartDefrag to run constantly, using up system resources, you can run it or another defragger at scheduled times. The question is, how often should you defrag a hard drive?

A drive becomes fragmented faster the more heavily you use it. So if you are constantly creating, altering, and deleting files all day, you will need to defrag more often. A crowded hard drive gets fragmented faster, too. It's easy to find a contiguous space for a file when there's lots of free space. But when free space is limited, a file is more likely to be split into multiple pieces.

Too Much of a Good Thing?

Defragging improves read-write times, but doing it too often can be counterproductive. Defragging re-writes nearly every file on your hard drive, putting maximum stress on the read-write mechanism. I can't say for sure, but it seems to make sense that excessively defragging would tend to wear out hard a drive faster.

Also, you should never defrag SSD or USB flash drives. It isn't necessary because these all-electronic drives don't have read-write heads that move around. Because SSD and USB drives have firmware that controls the placement of data on the disk, Windows cannot even "see" where the data is actually placed. A defragger can't either, so it's a pointless exercise. More importantly, flash memory can be read and written to only so many times before it wears out.

So, When Should I Defrag?

On Windows 7 and Vista, the defragger runs automatically and silently, so you shouldn't ever have to think about it. But if you have an external hard drive that isn't always connected to your Windows 7 or Vista computer, you may need to occasionally analyze and defrag it. (See below)

For those running Windows XP, most home users can get by with defragging once a month. Heavy users may want to defrag once a week. If you have a large hard drive that's mostly empty, you're probably better off waiting. But actually, you don't have to guess. The Windows defrag program has a feature that lets you analyze your drive, to see if you need to defrag. Here's how to check it:

  • Click Start, then click to open My Computer
  • Right-click on the hard drive icon (C:, D:, etc.) and select Properties
  • Click the Tools tab, the click the Defragment Now button.
  • Click Analyze Disk

The analyzer will tell you whether or not your hard drive is fragmented enough to warrant a defrag operation.

Analyze Before You Defrag

On Windows, the defragmenter can be set to run at a scheduled time, ideally when you are unlikely to be using the computer. Many third-party defraggers include scheduling functions, too.

What's your opinion about the best time to defrag a hard drive? Post your comment or question below...

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Most recent comments on "How Often Should I Defrag?"

(See all 25 comments for this article.)

Posted by:

13 Feb 2012

you don`t have this problem with linux

Posted by:

13 Feb 2012

I can't see the date when this article was written. Please put the date on your articles. Sometimes I am finding that I am reading an already old article. How old is this? "Why?" you ask. Because, "More importantly, flash memory can be read and written to only so many times before it wears out." is basically true, but modern SSDs, even flash based memory, will generally out last hard disks by a large margin. What you mention was true about 5 years ago (back in 2007). But stated against later SSDs that statement is now FUD. MTBFs on SSDs has shot through the roof. They are now into decades.

Posted by:

Jim Norley
13 Feb 2012

I just wanted to say thanks for your easy to understand article of defragging. It is something I don't normally even consider doing, but your description of pros and cons was certainly helpful to me. Thanks

Posted by:

13 Feb 2012

The answer to the question is a resounding: It depends. It really depends on how often you access documents, how often you download files, how often you install new programs. On a practical side, run the analyzer on whatever defrag program you have about once a week. If it says that your hard drive is too fragmented, then defrag the drive. Otherwise, check again in a week. Every day is certainly overkill.

One thing that you have to remember is that every hard drive has a mean time between breakdown (MTBB). That really isn't months and years, but is how many times it spins. The more often you defrag, the more use your hard drive gets.

Posted by:

14 Feb 2012

Hi Bob,
Thanks for your excellent article.You pretty well covered all of it.My own settings for defrag are very close to what you describe.Lots of activity on the system ,defragging is done more frequently ,more like bi-weekly.
One thing I should mention though:Windows 7 doesn't auto defrag SSDs -actually ,defrag for SSDs is automatically disabled, BUT, if people run a SSD with Vista,they should disable defrag for that drive.
Vista doesn't have the detection mechanism in place for SSDs ,unlike Win7.Not sure how much damage it would do ,but it could theoretically shorten the lifespan of the SSD.

Posted by:

Sharon Gogan
14 Feb 2012

Do Mac's need to be "Defragged" also? If they do what application do you suggest.
Thank you,

Posted by:

14 Feb 2012

I use a 3rd party defrag program, it's Defraggler from the fine people of Crap-cleaner.
It's totally free and has the option of a full defrag or a quick one.
I find that using the quick option works best (And it's really fast) There is also the option to turn off the computer after the defrag, very handy indeed.

Posted by:

14 Feb 2012

Dear Bob , I use Piriform Defraggler . I was defragging very frequently , to prevent computer slowdown . Maybe , that's not a good thing . I think that "check disk drive for errors" maybe can prevent an emergency Windows shutdown . I also defrag the freespace . Thank you . John

Posted by:

Bruce Tech Guy
14 Feb 2012

These days, I do a partial defrag of selected files and folders daily. These are files and folders that usually see a lot of writing and re-writing activity daily. But as far as running a general defragmenter to defrag the entire drive, that I do relatively infrequently.

This applies to my Win XP Pro Sp3 main disk and my most active secondary and external drives.

My new rule of thumb, regarding should a file or folder be a candidate for regular defrag: If I plan to access it more than two or three times in a few days, or use it on a regular or daily basis, then it is a good candidate to add to my list of selected folders to defrag. If it is data that I plan to access irregularly, then I just let it be.

My thinking is that for most of the data on my drives, it really makes no sense to do a full defrag regularly, because that amounts to a lot of disk activity, shuffling the data around to no great benefit. (IMO)

Posted by:

Gil Tyrelle
14 Feb 2012


One must N-E-V-E-R De-Fragment a Solid State Drive (SSD) - - EVER!!!

Posted by:

Daniel Levin
14 Feb 2012

Analysis for fragmentation per your instuction is a waste of time. Just running almost any defragmenter takes less than half the time of the analysis.
Incidentally, the fastest defragmenter is Disk Speedup by Glarysoft. Don't be fooled by the app name, it is a defragmenter.

Posted by:

P. Kruijer
14 Feb 2012

I do not understand why people do not use an application to do this defrag for them. I use since years an application which does all this defrag for me, it is called "Diskeeper 2011" I know it cost money, but you do not have to worry anymore.

Posted by:

samikkannu a.v.
14 Feb 2012

the article is very much helpful & informative for a layman like me who have been wondering all along if it is advisable to defrag quite often ; i have Norton Utilities which takes care of this job now ; though i used to work with my pc for more than 5 hrs a day i, having read this piece , shall hereafter defrag my hard drives-- both inbuilt & external --[Seagate 1 tb ] once a month .

Posted by:

14 Feb 2012

I guess I've been defragging too much -- about once a day, using the Pirform application "Degfraggler" on the "quick defrag" setting. My computer is fairly new, a 1 terabyte HD, and my thinking was that constant defragging would keep the system clear.

Having read your article, I'll defrag less frequently.

Posted by:

14 Feb 2012

HI Bob! Am I right to understand that defragging too often could be bad for my PC? Then, here is my question: Is it worst ro degrag let's say once a day than having a realtime defragger like the IOBit Smast Defragger running permantly. Thanks.

Posted by:

15 Feb 2012

I have discovered over the years that PC performance degrades noticeably when ever the disk is more than 65-70% full. Try to keep your disk drive under 50% for best performance.

I also use Auslogics Disk Defrag tool and Optimize my disk each time. The Optimize feature moves frequently used files to the fastest locations on the disk and improves performance.

An external drive can be quite useful for keeping your C: drive clean and

Posted by:

15 Feb 2012

In a "Windows 7 Forum" discussion on CNET one fella mentioned the following (which prompted me to quit using my third-party defragger):
Windows Vista and Windows 7 have what is know as Pre-Fetch. This is basically a list of all the applications you use more often. Windows creates and updates this list often, depending on what you do with your computer. Because of this, it sets your most used applications to be access faster.
...other defragmenters see this as fragmented files...when you run them, you are un-doing the possition of applications based on the Prefetch...Then after 3 days or so, Windows will relocate the Prefetch applications again.
You will noticed a slight slow down for about 3 day - until Windows re-builds the Prefetch and repositions the applications more often used.

Posted by:

24 Feb 2012

You can never defrag too often. Bad HDD's fail and good ones seem to last forever. I have some that are 10+ years old still serving duty as main drives for servers built with Pentium 3's. My point is dont be stingy on the defraggin!!!

My main Desktop is a budget Athlon x2 4400+ with 3 gigs of DDR2, Geforce 220 GT, 220 gig main drive, and a 500 gig secondary drive. This PC will boot in less than 45 seconds and runs smooth and fast considering its internals. It always outperforms similar systems according to PC Pitstops Pit Test. I use the Pit test to help me keep all our PC's at home working properly. It gives consistent test scores that seem to be inline with the overall feel of the system. Ive trusted them for years.

My point? The Pit test scored my main HDD with 78 MB/sec. The average is 50. Thats a huge boost. Im also seeing the drives great performance help the processor operate more efficently.

Im using Auslogics disk defrag. After im done with my pc for the day I open up Auslogics, select defrag and optimize, then check the box that says shutdown after complete. Im always defragged and OPTIMIZED. I enjoyed the article but cant help to wonder........Are we still debating this??? Is this real?? Who in their right mind would ever say you should never defrag? These people who never defrag are suffering with lousy performance that increasingly gets worse for what? So they can suffer with that terrible performance for a few more years? How much time have they wasted in that HDD life buy allowing it to operate so inefficiently? In my opinion defragging constantly everyday like I do is less damaging to a HDD than letting it get fragmented.

Posted by:

23 Jul 2012

I spend lots of time researching stocks, and get a lot of newsletters about them. All in addition to the bs emails my friends send. Lots of stuff goes in and out of my computer, so I like to keep up with maintenance - but I don't do updates or scans automatically. I consider auto updating to be a dangerous practice, since you have no control over what you are getting. How do you think you got all those search engines, browsers, and task bars you never asked for?

I try to do it all manually, but keep it organized and simple so that it doesn't take forever. I have a schedule that goes something like this:
Mon,Wed,Fri: Run full scan with anti-virus at end of day and use auto-shutdown when finished.
Tues,Thur,Sat: run Malwarebytes full scan during lunch.
Every morning: update antivirus, and antimalware.
Sunday: Run full anti-malware, full anti-virus, system tools full disk check, CCleaner registry cleaner, then disk cleaner, and finally Iobit smart-defrag full optimize.

All this on Sunday goes on while I watch a Nascar race or NFL game, so it doesn't require additional time.

Over the years, I found that I lost more hard drives from viruses, and spyware than from disk
mechanical failure. Since I established this maintenance program, I have not lost a single drive, and I don't have to worry about some update popping up right when I"m in the middle of doing something.

Posted by:

Auna Blessing
05 Aug 2016

I disagree with you about defragmenting. It should be done often. We do it daily, because we play a lot of games, both online and PC games. It improves performance significantly. Our hard disks last for a very long time. Also, analyzing the disk is a waste of time, because by the time that it says there is a problem you will need a professional to take care of it! And all that time you wasted, your computer could have been running faster. Sometimes I will defrag more than once, because I like to get my time down to about twenty minutes. You have a lot of fragmented files if it takes longer than that. And I know your analyzer will say you don't need to do anything, but you should. Plus, you sound like a bit of a hypocrite, saying that you have this program that defrags constantly, and we should do it weekly or monthly, or whenever our system is so severely backed up that the analyzer says to do it. Come on, be honest with your readers! You do it daily, you do it often. Telling us to do the complete opposite seems a bit weird on your part. I'm going to be wary of your advice from now on, after this. Also, analyzing the disk is wasteful if that could really wear it out. Just defrag already!

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