Best Free Disk Defragmenters Tested


Ask a PC specialist or technician on how to make your slow, usually old computer to run faster again and they will advice you a common thing – defrag. Though defragmentation is not the only solution to the problem, fragmentation is a common problem to almost every slow computer. That’s why we see dozens of defragmenters offering solution, some were free, some you need to pay to be able to use its full capabilities. For this article, we will examine some of the most popular free disk defragmenter to help you find which defragmenter is the best.


What is file fragmentation and defragmentation?

Let say you have a new computer. When you install and/or copy files to your hard drive, files and file fragments are copied and written next to each other (Figure 1). This is because there is plenty of free space.

Figure 1


Then you begin uninstalling and/or deleting files. Your hard drive now looks like this (Figure 2). There are now free spaces between files.

disk defrag-fig2

Figure 2


And then you install new applications, or copy plenty of files, or edit a couple of videos. The new file will be copied on free space in-between, and if the free space is not enough, it will look for another free space to write the remaining part of the file, thus making the file fragmented (Figure 3).

disk defrag-fig3

Figure 3


If the file is fragmented, when you access the file, the hard drive will look on another sector of your drive to find the remaining pieces of the particular file, making it slower and took a while load and open. Otherwise if the file is not fragmented, the hard drive will not have to look somewhere else to find the remaining pieces of the file, making it faster to load and open the file.


Defragging/defragmenting is a process of putting together file fragments to speed up file access. That’s what disk defragmenter tool do. Other disk defragmenter also consolidate free space to avoid fragmentation of new files and put the most frequently accessed file to the fastest accessible part of the hard drive, usually the boot files (Figure 4).

disk defrag-fig4

Figure 4


Test System


Processor           –         Intel Celeron G550 2.6 GHz Dual-core
Memory              –        Geil 2GB DDR3-1600
Hard drive          –        Seagate 500GB hard disk, 55 GB System Drive
Video Card         –       nVidia GeForce 9600GT 512MB DDR3, Forceware 306.97

– The 55 GB System Drive serves also as our test drive. All the applications and files used for testing are all in this drive.



Operating System       –     Microsoft Windows 7 x64 with Service Pack 1

Disk Defragmenters

  • Auslogics Disk Defrag 3.6.0
  • Defraggler 2.12.628
  • MyDefrag 4.3.1
  • O&O Defrag Free Edition 14.1.431
  • Puran Defrag 7.5
  • Smart Defrag 2.6
  • Ultra Defrag 5.1.1
  • Windows Disk Defragmenter



The following is the sequence we followed to do the tests for each disk defragmenter.

  1. Install all the necessary software, drivers, and all the disk defragmenter tools.
  2. Copy all the files that will be use for testing and running the benchmark.
  3. Create a disk image of the system drive.
  4. Do all the tests. This serves as our “Before” defragmenting results.
  5. Restore the image file of the system drive.
  6. Defrag using the Disk Defragmenter #N.
  7. Do all the tests. This serves as “Disk Defragmenter #N” results.
  8. Rerun step 5-8 using the next disk defragmenter.


– We assigned points for each disk defragmenter to determine the best and worst performer for each test. We give 8 points for the best and deduct 1 point for each succeeding defragmenter. In case of tie, all the tied defragmenter will have the same point.

– We included the “Before” defragmenting on the ranking, which means “Before” will also get points.

– We rounded down the decimals of time in seconds. 5.6s and 5.1s are both 5s. In real time, you will not really feel the difference of 0.5s, 0.8s, even 0.1s so we decided to round down the decimals.

– Aside from the defragmenting, we also used the optimization feature of the defragmenter, if available.

– All time related tests were measured using a stopwatch.


Tests and Results

Drive Status

We used defraggler to determine the disk status on “Before” and after defragging.

 Fragmented FilesTotal FragmentsFragmentation %Free Space
Before2781 (7.3GB)26528156.6 GB
Windows Disk Defragmenter68 (1.6G)64627.3 GB
UltraDefrag46 (2.7GB)25847.3 GB
Smart Defrag 256 (1.5GB)160337.3 GB
Puran Defrag59 (144 MB)31607.45 GB
O&O Defrag Free41 (36.5 MB)29307.4 GB
MyDefrag39 (33 MB)13107.4 GB
Defraggler40 (32.5)30307.3 GB
Auslogics Disk Defrag47 (37.8 MB)18907.3 GB


Each defragmenter reduced the fragmented files and size, the total fragments, and the percentage of fragmentation. But we found out that the number of fragmented files, the total fragments, and its percentage are not always relative to each other. Having lesser fragmented files doesn’t necessarily mean that you will also get to have lesser fragments and lesser percentage. Take a look at UltraDefrag and Smart Defrag for example. UltraDefrag has lesser fragmented files and yet bigger fragmented file size. It also has lesser total fragments and yet higher percentage of file fragmentation. We also found out that you can also save additional free space after defragging. To be honest, I only found this out after doing the tests.

We didn’t include these results in our scoring because we are after for the actual results and benefits.


Boot-up and Shut down

We used BootTimer to measure the boot-up time and a stopwatch for the shut down.


Defragging won’t guarantee faster boot-up. Here, O&O Defrag improve the boot-up time by 9 seconds, but Auslogics, MyDefrag, and UltraDefrag took longer boot-up time than before defragging. But every defragmenter took shorter time on shutdown compared to before defragging.


Disk Performance




Defraggler’s built-in benchmark tool guarantee us that defragging will improve disk’s random read speed, but CrytalDiskMark didn’t. Some defragmenter improved the random read speed, but worsen the sequential write.


PCMark Vantage


Defraggler gets ahead of the rest of the defragmenters followed by Auslogics Disk Defrag.  MyDefrag, UltraDefrag, Smart Defrag gets lower points than before defragging, but the difference were small and it is almost negligible.

  1. Have practically used all the software mentioned but never heard of OS Defrag. Really never had any real or advantageous performance change on my PC with the others so I decided to us OS Defrag and it performs very well. No problems what so ever and speed-ed up my boot time by 7 seconds which is GREAT. Also like the fact that it redistributes files in 3 sections and this definitely helps especially when booting up. The FREE version is very handy and considering on getting the PRO paid version since it has a couple of options that can be very useful. Thanks for your valuable info and the time you put into such an in-deep analysis on defragglers. Wish that other tech’s that recommend this kind of software would do the same as you have done so again THANKS A MILLION…….

    George Melendez
    Humacao, Puerto Rico

    Toshiba Satellite P845-S4200
    Intel Core i5
    6GB DDR3-1600 memory
    750 GB Hard Disc
    Windows 7-64 Home Premium

  2. I mentioned OS Defrag and it should be O&O Defrag Free Edition…. sorry about that. As you can see, I never heard of it so I spelled it wrong.

  3. thanks fro the excleent break down of defraging but being a ludite of sorts i repeatedly fail to download and install O&O Defrag so if you could recommend a second defrager from teh tests you did I would be grateful. As others anyone that would help with my slow bootup would be great. I have used Auglogics and Smart to little avail in the past.
    thanks again,

    • If you really want to speed up your boot time just install SOLUTO…. get it here >>>> … This little baby will help you control your boot time with ease. A defragger, well I use O&O Defrag Free and have been for a year but if you have problems downloading and installing then install Auslogics. Defragging does very little when you speak of lowering boot time. I have only experienced lower time with O&O Defrag.

    • i recommend auslogics disk defrag as second defragger. you can also check the best performer for specific task.

  4. Thanks for the benchmarking, and the hard work. Granted spinning disks are facing a lot of competition from SSD’s, but there’s a pile of them around and will be for years, so I like to watch what’s going on. I recently came across another site that just ran most of the same defragmentation tools through another set of benchmarks. Together, I think you get a pretty good picture of what’s going on.

  5. Incredible job here!! I have searched many webs and this is the best and most objective article written on defragmentars that I have seen. 10 of 10

  6. Great work on the testing, but I have a bit of a presentation gripe — you should always display -full- graphs from zero on each axis. Bad form; can be unintentionally misleading or intentionally misleading.


  7. I think there are missing informations and tests with different program options. Some programs has powerful setting, that can considerably change results. In this test it’s not known, what settings were used. Therefore results in this test are not precise, and has less worth to say, what is good software. There’s need to do more test with some settings change, to proclaim results like this. Because then you can see that order of software would be really different.

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