3 Ways to Split and Join Big Files

The size of files we use today is bigger than even a few years ago. Multi Megapixel digital images can be in the tens of Megabytes, small HD video clips can be in the hundreds, and several types of files like ISO disc images and movie files can easily run into the Gigabyte’s.

One of the issues these days is transferring files across the internet because certain limits apply depending on what you’re trying to do. Take sending a 100MB video clip to somebody via email for example. Most email services including popular ones like Gmail and Hotmail have some sort of cap on the size of attachments, usually around 25MB, so sending a video file larger than that wouldn’t be possible.

A similar story arises when using a free file hosting service like MediaFire, the free user limit is around 200MB and sending a larger single file just isn’t possible. But whether it’s a file that’s too big to upload where you want, or if you have to back up a big that won’t fit on to a single CD or DVD or even USB stick, there’s one rather simple solution; split the file into smaller chunks! Using the file splitting method you can perhaps split a 10 GB file into 4.3GB parts, which can then be stored on 3 DVD-ROM’s by your burning software. If you have that 100MB video clip to email to your family or friends, it can be split it into 5 parts of 20MB each therefore keeping it under the email file attachment limit. This is the advantage of splitting files where otherwise you would be in a bit of trouble.

There are different ways to accomplish the splitting of files and we’ll show you 3 of them here:

1. HJ-Split

One of the most popular tools to split files into smaller chunks over the years is a freeware program called HJSplit. It’s a small and portable standalone executable and is compatible with windows NT up to Windows 7 64-bit. There are also multi platform versions available for Linux, Mac, Amiga etc, and you can also split and join between the different systems. Just download, extract the zip file and run hjsplit.exe.


Using HJSplit to split and join files is very easy and and the interface, as you can see, is not complicated to get around at all. To split a big file, just click on the Split button, and locate the file that you want to split into chunks. The output files will be created in the same folder as the input file unless you choose differently with the Output button. The size of each output file is determined by entering the size into the box, make sure it’s set to Megabytes. Then click Start to begin the splitting process.

File Split

The split up files will be renamed with a new extension of .001, .002, .003 etc. To join back the files, you or whoever the files are being sent to will also need the HJSplit executable, and you simply click on the Join button. All you have to do is click Input file and select the first file which will be the one that ends with the .001 extension. All the files to join need to be in the same directory and if they are, will be recognized as part of the collection to be rejoined. Output will let you choose another destination for the joined file.

The Compare option will let you compare 2 different files to see if they are the same byte for byte. Checksum is a useful option where you can create MD5 values for the files you have just split, give them to the recipient and they can then check the integrity of the files they receive to make sure they’re 100% identical to the files you sent.

There is also a tiny utility for download called HJ Join which is only 44Kb and has no graphical interface. All you need to do is place all the .001, .002 etc files in the same folder and the program will automatically join them without user interaction. Useful for inexperienced users you’re send split files to.

Download HJSplit and HJ Join

2. Fastest File Splitter and Joiner

Another portable tool called FFSJ (Fastest File Splitter and Joiner) is a good alternative to HJSplit because HJSplit seems to take longer than it really should to split files. Also there are a few reports of it not handling multi Gigabyte files too well in some cases. FFSJ is fast, easy to use, and has a couple of useful extra features for good measure. There is also an installer version that adds context menu entries to enable splitting and joining by right clicking on a file.

Fast File Splitter and Joiner splitting window

Splitting a file is again easy and you simply enter the file to split and choose a destination folder if the default isn’t desirable. Splitting can be achieved by either making each output chunk the same size or splitting after a set size is reached. The last option is best when trying to fully fill up optical media like CD’s and DVD’s. A valuable security option is the ability to encrypt the files that get split with a password, but make sure you give it to anybody else you send the files to!

Joining the files is just a case of selecting the first file in the split file collection (.001 or .__a for encrypted files), choosing the output file name and clicking the button. Something this program can do is gather split parts from different locations by ticking the box. When it’s joined as many consecutive files it can from the current location, you will be asked to point to another folder where the next files are kept. There is also the MD5 tab where you can calculate an MD5 checksum for each split file.

Download Fastest File Splitter and Joiner

3. Using an archiver

Another common way of splitting files into smaller parts is something that’s often done when you download games, movies etc from the internet, and that is by using a multi part archive. There are several around to do this, and we’ve done a speed and compression test on a number of archivers which you might want to look at. For this example we’ll use the popular open source archiving tool 7zip which you need to download and install if you don’t have it.

Right click on the file to split and go to 7zip -> “Add to archive…”.

Split with 7zip

Unless you’re splitting a large document which can be compressed, it’s best to select the “Compression level” as Store to save time. To choose the size to split the files into, enter the number into the box and add a letter to indicate the size format, M=Megabyte, G=Gigabyte. You can also enter multiple different sizes by inserting a space in between each size unit. A password can be used for extra security by using the encryption boxes.

To join the files back again, simply double click the first file (.001) and extract through the programs interface. Alternatively right click the first file and go to 7zip -> Extract…

A Quick Splitting and Joining Comparison

As some file splitting programs could perform faster than others, we thought it would be useful to run a quick comparison of a few tools to see if any stand out. The tools included were; GSplit 3, HJSplit, Fastest File Splitter and Joiner (FFSJ), Free File Splitter and 7-Zip using zip store compression. A 3.45GB ISO file was split into 200MB chunks from one 7200RPM hard drive to another, and then joined again in the opposite direction using Windows 7 64-bit.

7-Zip: Split time: 20 seconds | Join time: 25 seconds

FFSJ: Split time: 24 seconds | Join time: 30 seconds

GSplit 3: Split time: 20 seconds | Join time: 30 seconds

HJSplit: Split time: 24 minutes 34 seconds | Join time: 1 minute 38 seconds

Free File Splitter: Split time: 16 seconds | Join time: 25 seconds

Well, one tool really did stand out for all the wrong reasons which was HJSplit. We tested it 2 or 3 times on different machines but the results were similar, it really did take several minutes to split the same file as the others who managed it in somewhere between 16 and 24 seconds. It also occupied 1 whole processor core during that time. As you can see, the other tools were all quite close and Free File Splitter is well worth checking out for its speed. Also, using a standard archiver to store a split zip file compares well and the added advantage is you probably have something like 7-Zip installed on your system anyway.

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