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Best disk defragmenter tools 2021

Best disk defragmenter tools 2021
(Image credit: Defraggler)

Trying to get the most out of your computer? Install one of the best disk defragmenter tools and you should find that your PC speeds up nicely. The defrag tool will sort out your hard disk – an important part of your home computer or laptop – organising it into a more efficient structure.

Not every set-up actually has a hard disk these days, as a lot of computer builds use SSDs. But hard disks are still used in plenty of budget PCs and older laptops, mostly as a form of secondary or external storage. This is where the best disk defragmenter tools and software programs come into play, as they can help maintain these older bits of hardware.

Hard disks offer huge storage capacities at a relatively low cost, but computers tend to store data on these disks in a disordered fashion. This means that when your PC tries to access that data again, the various disks have to be shuffled around, hence why your computer might run at slower speeds. Defragmenters can help with this problem, as they collate all of that data into one space on the disk. The best defrag packages offer a range of other features too, like hard disk health modules and SSD-tweaking utilities.

In our round-up of the best defragmenter tools, we’ve placed O&O at the top of the list because it has a huge range of features and a straightforward design. However, if you’re specifically looking for the best free defragmenter, we recommend Glarysoft Disk SpeedUp, as its core set of features can be accessed without payment.

Computer still not performing as you’d like? Have a look through our round-up of the best repair software for PCs as well. And if you’re in need of even more storage, check out our guide to the best external hard drives

1. O&O Defrag: Best disk defragmenter tool overall

o&o smart defrag: Best disk defragmenter overall

(Image credit: o&o smart defrag)

O&O Defrag

If you want loads of features and a clean design, you can't beat O&O Defrag

Huge range of features
Updated hard disk and SSD algorithms
Straightforward design
A little expensive

The powerful algorithms, broad range of hard disk and SSD features and the sensible, straightforward interface make O&O Defrag the top choice. O&O’s Defrag application has been one of the most popular defrag tools for years now, and it’s no wonder – this utility is easy to use and packed with powerful settings.

The latest iteration, version 24, includes new features that make the optimization process smoother and more powerful. The underlying defrag engine has been reconfigured to support new features in Windows 10, and a new installation method picks the best settings for your PC – so you can install and start using the app without any extra configuration. There are updated methods for optimizing and extending the lifespan of SSDs too, which is important – many of us use SSDs, but many apps are still based around hard disks.

These new features are bolstered by powerful, familiar functionality. The core defrag algorithm is market-leading and has been made faster in this release, and the app has a disk cleaning tool to remove temporary and unnecessary files. It’s got automatic background and scheduled functionality, filters so you can easily find your most fragmented files, and you can access lifetime statistics so you can see exactly what space and time you’ve gained.

The app is straightforward, with clear options, quick defrag features and graphics that show you the state of your drives. Extra features can inspect individual file clusters, determine file positions and throttle system resources so you can still use your PC while the app works. You can even optimize the files required when your PC boots.

This app’s only real weakness is its lack of a free edition, but the Professional, Workstation and Server versions are affordable, with prices that range from $30 to $200 – and those latter apps give additional features for administrators who want to keep a network of PCs in top condition which go a long way to justifying the higher prices.

2. Defraggler: Best for overall PC health

Defraggler: Best disk defragmenter for overall PC health

(Image credit: Defraggler)


This one will give your whole PC a decent health-check

Slick hard disk and SSD options
Supports scheduling
Includes benchmarking
Pro version is expensive

Defraggler’s free version is an effective tool for defragging hard drives without weighing down your system, but we’d recommend that app bundle – you get more features alongside extra tools that can manage your entire system.

Defraggler is made by a company called Piriform, and that firm is one of the most experienced when it comes to PC optimization and management – it also produces CCleaner, Recuva and Speccy, which are well-known tools for looking after your system.

Piriform’s defrag tool has a free version, which serves up all of the key options for keeping your hard disk in shape – and it can use its algorithms to keep your SSDs organised, too. It works with external drives as well as internal disks, and you can defragment specific drives and folders. It has a benchmark tool to evaluate your performance improvements, and you can analyze drives to determine whether or not you need to run any defrag processes. Scheduling is supported, but the app can’t start defragmentations when your system is idle.

Defraggler serves up straightforward charts to illustrate what’s going on with your drives. Upgrading to Piriform’s Professional edition costs a hefty $25 and nets you better support and automatic updating, and spending an affordable $30 will get you Piriform’s entire family of apps – Defraggler Professional will be included alongside CCleaner, Speccy and Recuva’s professional versions. That’s a far better deal.

3. IOBit Smart Defrag 6: Best defrag for gamers

iobit smart defrag: Best disk defragmenter for gamers

(Image credit: iobit smart defrag)

IOBit Smart Defrag 6

If you're running a gaming rig and need an HDD clean, this is for you

Game-specific options
Loads of features elsewhere
Pro version is cheap
Ads included in free version
Tries to install extra software

IOBit’s Smart Defrag lives up to its name, with options that allow for a huge amount of customization on an app-specific basis – handy if you’re a gamer or professional user who wants to keep certain software running at peak performance. It’s even got a Game Optimize mode that can be used to deliver a smoother and faster gaming experience.

Beyond that, Smart Defrag has an impressive slate of options – you can defrag entire drives, specific files and folders or specific apps, or defrag your system files when you boot the PC, so the computer has been optimised before you start work. Smart Defrag works with hard disks and SSDs, and it supports scheduled scans.

Handily, Smart Defrag has a free version, but be aware that you’ll have to skip past some extra apps during the installation process and deal with ads when you boot the software. This app also can’t perform defrags when your system is idling. The Pro version costs a reasonable $12 and includes new features, like disk health monitoring and specific large file defrags. This is a good defrag app, and it’s a great option for gamers.

4. Puran Defrag: Easiest to use

Puran Defrag: Best disk defragmenter for ease of use

(Image credit: Puran Defrag)

Puran Defrag

If you need easy, rather than feature-filled, then Puran is a perfect fit

Effective, usable interface
Registry and scheduling tools
Utilities suite available
No portable option
More features available elsewhere

Puran Defrag is the best option if you’re not a particularly advanced PC user but if you still want an app that can keep your hard disks and SSDs in top condition.

This free tool has an impressively slick and simple interface that makes it easy to get started. Booting the tool loads up a clear list of your drives, a map of their storage setup and obvious options to analyze and defrag the disks. There are options to make the task low-priority to stop it impacting on your system’s performance, to shut down the PC after the defrag has completed and to customize the boot, defrag and disk-checking process.

There are more options if you delve into Puran’s extra tabs. There are detailed scheduling options, Registry defragmentation tools, an intelligent optimizer to increase system speed and options to exclude specific files or files at certain sizes from operations. Sadly, the app doesn’t have a portable version and can’t manually run free space defrags. And, while it’s easy to use, other apps do have more features and slicker interfaces – and offer more detail when it comes to seeing exactly what’s been defragged.

Puran Defrag’s free version is an effective tool if you don’t want something too complicated, and you can also download Puran’s free Utilities suite, which also serves up tools for disk cleaning, file recovery, gaming, disk wiping and much more.

5. Auslogics Disk Defrag: Best disk defragmenter for pro-PC users

Auslogics defragmenter: Best disk defragmenter for pro PC users

(Image credit: Auslogics defragmenter)

Auslogics Disk Defrag

If you're a pro-PC user this software will give you more control

Very fast operation
Broad range of options
Works with SSDs
Potentially confusing interface
Some features missing in free version

This app places a huge emphasis on getting your defrag operations completed quickly – Auslogics boasts that it usually takes less than ten minutes to complete operations on a standard hard disk.

This tool is ideal for those in a hurry, then, and it has a good slate of features elsewhere. It has specific routines for different kinds of drives, it can remove temporary and unneeded system files, and its operations can be scheduled and set to run when your system is idle.

Elsewhere, Auslogics can exclude files and folders from defrag runs, run analyses and quick defrag operations, provide reports on your PC’s status and even just defrag the files and applications that you use most often. There are more options deep within the app, including settings to change how the charts look, use different features for SSDs and move system files around on your hard disk – to improve boot times.

The free version is packed with features, and there aren’t many downsides – the only issue is that the interface and the broad selection of options may be confusing for less knowledgeable users. If you spend $25 on the Pro version you get loads more, including specific SSD algorithms, better disk cleanup options and free space wiping alongside better scheduling options and a license for use on three different PCs.

There are free applications out there that have more options, but Auslogics’ Pro version is packed with versatility, and the free and paid versions are both extremely fast. This is the ideal defrag tool if you have a need for speed.

6. Glarysoft Disk SpeedUp: Best free option

Glarysoft disk speedup: Best disk defragmenter for free

(Image credit: Glarysoft disk speedup)

Glarysoft Disk SpeedUp

If you'd rather pay nothing, and put up with fewer features, Glarysoft has you covered

Primarily a free tool
Good core functionality
Automatic and scheduled defrags supported
Misses some advanced features
Doesn’t work on removable drives

For most of us, though, Glarysoft’s free version will be more than adequate thanks to its effective design and decent functionality. It’s our top choice if you just want a free defrag tool.

Glarysoft Disk SpeedUp is the best option if you want a free, unfussy and effective defrag tool. Booting the software loads up a clear picture of your drive health and clear options for improving it – pick a drive and you can run analysis, defrag the drive, optimize the storage and choose to turn your PC off after the operations are complete.

Glarysoft’s app supports individual file and folder defrag operations, and you can run operations with different levels of priority – so you can speed things up if you want the defrags to finish quickly or slow them down if you’d like to keep working while the app does its thing. This tool can automatically start defrag processes if your system is idle, and you can choose how long it needs to be idle for before processes begin, and basic scheduling is also supported.

The fact that Disk SpeedUp is free means that some functionality is missing. It doesn’t work on removeable drives, it doesn’t integrate into Windows Explorer and it doesn’t have a duplicate file finder, and other apps offer more customization and faster operations. It does have a small advert in the corner, too, but it’s far less intrusive here than on other free tools.

Happily, though, this app has ample functionality for most mainstream defrag operations. It also forms part of Glary Utilities, which is a suite of more than twenty tools for PC optimization. A Pro version is available for $20, and it includes free technical support, commercial usage rights and enhanced optimization features – including for Disk SpeedUp.

What is file system fragmentation?

Any data you save on your computer’s hard drive – from a program or Word document to the computer’s operating system itself – is stored as one or more files, also known as blocks. By default, your computer tries to store new files as close to the front of the hard drive as possible, making them easy to access. In an ideal situation, all the files for a particular program would be stored neatly next to each other forever. However, that is rarely the case, especially if you regularly download and create new files on your computer.

A new text document, for example, is initially stored on your hard drive as files located right next to each other. If you add new program files to your computer before you return to work on this document later, the new files are stored in the next available space – right next to your original text document files. When you edit your original text document, adding to it, renaming it or otherwise altering it, more data needs to be written to its files. Anything new you save goes into a new file space, after your new program files, leaving your text document files fragmented. Now, when you tell your computer to open that text document, it must look in multiple places to find the relevant files.

Fragmentation can also occur when you delete files and then create new ones, saving them where the recently deleted files were. Your computer will start saving new files as close to the front of the hard drive as it can, but if the new files are larger than the freshly deleted space, your computer will fill up that space then move the rest to the next available space, splitting them up. Finding and opening multiple files can take extra time and processing power, which can eventually lead to slowed computer performance.

Though this is a regularly occurring process that doesn’t endanger the health of your hard drive, it can be annoying. Luckily, the problem of fragmentation isn’t too difficult to fix, thanks to disk defragmenter software. You can run it on your hard drive any time you suspect your computer is suffering slowdown as a result of fragmentation. Just be sure you don’t use the software on Mac computers or solid-state drives.

External and Portable storage defragging

In addition to ensuring your Windows machine is regularly defragged and running optimally, we also recommend defragging your external hard disk drives (HDDs). Because these drives don’t typically stay connected to your computer like the one built into your machine, they’re less likely to receive regular maintenance. If you use your external HDD frequently for saving and accessing programs and data, this is especially important to maintain.

In contrast, you do not need to run defragging software on a flash drive (also known as a jump, USB or thumb drive) or on an external SSD. These types of drives are physically different from traditional hard disk drives and don’t have to be defragmented; in fact, the process is usually damaging to them, potentially resulting in a loss of data or a ruined device.

On a side note, you can save your disk defragmenter software onto an external drive. You don’t have to save it onto the specific drive you wish to run it on. Keeping your software stored externally can be convenient in case your computer crashes, or in case you travel frequently and want to run the software on multiple computers. If the latter is true, you’ll want to make sure the software has enough licenses when you initially purchase it to be compatible.

Auslogics defragmenter

(Image credit: Auslogics defragmenter)

Why you don't need to defrag Macs

When you search online for disk defrag software, you’ll see a million returns for defragging a Windows machine and few, if any, for a Mac. You may be curious why this is, but the answer is fairly simple: the file system within a Mac hard disk drive (HDD) is designed differently from one on a Windows computer. Macs actually defrag themselves automatically with built-in utilities, especially if it’s a newer version of the Mac operating system (anything after 10.2). New Mac OS versions automatically check for fragmentation every time you access a file or program.

The only point at which you should be considering defragging a standard hard disk drive on your Mac computer is when less than 10% of storage space is available. When your HDD is this full, Mac OS is commonly unable to run its usual defragmentation program automatically. However, we recommend periodically going through your hard drive to delete old or unwanted files and programs to keep as much space available as possible, or to purchase a larger HDD that better suits your storage needs.

And as we’ve stated elsewhere in this article, you should never run disk defragmenter software on a solid-state drive (SSD). These drives are built differently and don’t fragment – plus, they are designed only to handle a limited quantity of writes and defrag software can lead to SSD damage or failure.

Freeware vs. Paid defrag software: which is best?

With so many free disk defrag options on the market, it’s hard to reconcile paying as much as $50 for a program. There is a large variety of free options available, and we tested a couple of them alongside some paid options. While we found that paid options were more robust and easier to use, the free options we tested were comparable in most areas, though they lacked some convenient features, like an SSD optimizer and duplicate file finder, weren’t as intuitive and had limited customer support options.

In addition to generally lacking functionality, freeware can also be a hassle to download. It may be part of a larger suite of programs, come with bloatware or malware, have ads or even appear free but really be a limited free trial that you’ll eventually need to pay for in order to access the program’s complete functionality. Free programs usually don’t have many informational resources regarding the application on their website either, so if you don’t understand something or need help troubleshooting an issue, it may be more difficult to get a solution.

Because freeware developers aren’t expecting payment for these applications, they are less incentivized to provide a well-rounded program to you. They may also include ads and not place much priority on technical support for the application.

iobit smart defrag

(Image credit: iobit smart defrag)

What to consider with disk defragmenter software

Ease of Use
Most disk defrag programs produce comparable results if you run them using the default settings. If you want to run advanced diagnostics or prefer to see more detailed information, many professional defragmentation applications offer informative dashboards and one-step access to your computer’s most critical functions.

Scheduling Features
Most professional disk defragmenters allow you to schedule specific times, including at night, to scan your computer. After all, who wants to wait through an hours-long process when you could sleep through the whole thing instead?

Few people perform system maintenance on their computer as frequently as they should. It’s often time-consuming and rarely fun. And what’s more, it can seem like a daunting task to novice computer users, or they may not even know it needs to be done regularly. If you frequently use your computer, especially to save, install or remove data, you also need to defrag it. Scheduling a set day and time to run the software is an effortless way to keep your computer running efficiently. The defragmenting process can take several hours, so you may want to have it run overnight so it’s not competing against you when you need to use other software.

Driver & Registry Scans
Professional applications do more than defragment your computer. They also check driver and registry settings. Often, professional disk defrag programs bundle driver and registry checks along with the software in one tidy package. An application with these functions helps ensure that your system has a chance to run efficiently.

Archival Features
Many defragmenters offer archiving. This feature works like a hyper-intelligent housekeeper, noting which items you regularly use and those you don’t. Then, during defragmentation, it groups and stores the older data in a specific location “behind” your most commonly-used files so they aren’t in the way. Not all of the programs in our comparison offer this, but it can make a substantial difference in your computer’s storage space and speed.

Software Size
When it comes to computer optimization software, a program with a smaller file size is usually better. Generally speaking, these programs don’t take up much space, unless you opt for a bunch of extras. Look for programs that require less than 1 percent of the free space on your hard drive to function.

When you check the file size of defragmenting applications, you may notice a few numbers listed. Most developers list the size of the downloaded file and the amount of RAM and hard disk space needed to successfully install the application. You may also see a figure that indicates how much available room you’ll need to run the application.

Manual vs. Scheduled

You have full control over when your disk defragmenter program runs – you can put it on a schedule or use it manually whenever you need. Both options have pros and cons, and learning the benefits and downsides to each can help you use the software the most effective and efficient way for your situation.

When you set up a schedule for the software to run, you don’t have to stress over slow performance creeping up every few months or wonder why files are taking longer to access or run. Instead, you can rest assured that your hard drive is optimized. It’s a good idea to schedule your disk defrag software to run if you want to keep your computer healthy but aren’t very tech-savvy. Most of the programs we reviewed are easy enough to use, with clearly labeled buttons. Some even have guides that walk you through the entire process.

If you are an advanced user familiar with the ins and outs of this type of software, you are better off running the program manually. That way, you don’t have to worry about the software running scans and repairs it may not need. When you run it manually, you also have more granular control over the process, and you can run it on additional external hard drives if you want.

What is Boot Time Defrag?

Boot time defrag is typically only used by advanced users who are extremely knowledgeable about computers. By definition, boot time is the time between when you hit the power button and when your computer is ready to use. During this time, your computer starts executing instructions such as loading its operating system and connecting with peripherals like the mouse and keyboard. In a matter of moments, your desktop computer – or laptop or smartphone – is ready to use. On old computers, this process took several minutes, but with newer computers, it only takes a few moments.

Some people say that using defragging software during your computer’s boot time doesn’t make a measurable improvement in performance and isn’t worth the effort. But the general thought behind running boot time software is that since those files are used often (every time you boot up your computer), they surely must experience fragmentation, and by defragging them, you can make the process faster by a few milliseconds.

If you don’t want to mess with these files or deal with the risks of doing so, there are other things you can do to speed up your computer’s boot time. The best thing you can do is to disable programs that launch at startup. Yes, it’s convenient to have all your favorite programs open every time you turn your computer on, but it takes a toll on the machine, and it’s not too difficult to open them manually as you need them. You can also set them to open automatically but at a delayed rate. In addition, you can delete desktop shortcuts, delete old files and programs, install antivirus software, and ensure your drivers are always up to date.

How to verify your defrag was successful

After spending money on a disk defragmenter program and running the software to help optimize your computer, it’s nice to have a way to verify that everything worked properly. If you have compatible software, the easiest way to verify this is by opening up the program and looking at the current map of your hard drive. This visual should show you the location of your files and how they are currently distributed. Luckily, it shouldn’t be difficult for users to understand.

If the defragmentation was successful, you should see your files all together in a singular area of your hard drive. If the defragmentation was not successful, you will likely see files scattered across the entire disk. Here, you should be able to view original and newly-moved data, ensuring it’s all on the ideal part of your computer’s hard drive.

Another way to check if your defragmentation worked, although not quite as definitive of an answer as opening up the software, is to see if the overall performance of your computer has improved since you ran your most recent defrag. If things seem to be running faster and more smoothly, and it feels like you can access and open files more quickly, it could mean that your defrag was successful.