How to Increase Floppy Disk Space and Capacity

Conventionally, it is thought that 3.5″ disks are only capable of holding 1.44MB of data. This can be a problem if you want to transfer a very large file and don’t have access to other methods of data transfer (CDRW, USB drive, etc.). However, it is possible to actually increase the total capacity of a diskette by as much as twenty percent. Other techniques can be used to increase the amount of information which can be stored on a disk as well.

A free program which can be used to expand the capacity of disks is FDFORMAT. It is an older program which works in Windows or DOS 3.2 (and newer versions). It is available for download on a few websites, sometimes within a file called “msoft17f.zip”. I found that it wouldn’t function properly in Windows XP, but worked fine when the computer was booted with a DOS 6.22 disk. It is important to use the correct command line parameters when using it, be sure to refer to the documentation files. Using the batch (.BAT) file included with it in the above-mentioned zip file, it formats a regular 1.44MB 3.5″ disk to 1.71MB, an almost 20% increase. Both in DOS 6.22 and Windows XP (after formatting it in DOS), I was able to fully utilize the disk space and access the files on it.

If you have any old 720K 3.5″ disks, this program can increase their capacity as well. When using the maximum track (/T:) parameter number mentioned in the documentation, the disk capacity increased to 830K, but the additional space couldn’t be used. However, when the /T: parameter was reduced to /T:80, the disk space was increased to 812K and it worked fine in DOS and XP. Chkdsk didn’t find any problems with the disk either. When I tried the 812K disk in an older computer with a 720K 3.5″ drive and DOS 2.11, the computer was unable to write to it.

Another program for increasing disk capacity is MAXI Disk, which is available for download (shareware) from Herne Data Systems. It is designed to work in Windows 3.1 or 95, and won’t function in DOS 6.22. It opened, but was unable to format the disks properly in Windows XP.

Aside from increasing the floppy disk’s actual capacity, some measures can also be taken to use the space more efficiently. You can use a file compression program (such as WinZip) to compress several files into one smaller file on the diskette. However, you will not be able to access the files from the disk without unzipping/decompressing them, which won’t be possible if you take them to another computer which doesn’t have compatible software to use for this purpose.

Another technique for increasing space is to avoid using directories (or “folders”). To test this, I just added an empty directory to a disk and found that the free space decreased by almost one kilobyte. While this is not a large amount of space, it is more than expected, and could add up if your disk has a complex set of directories/folders on it.

With some luck, you should be able to use these techniques to gain the extra disk space you need, rather than spending money on expensive Zip/USB/CD-R devices.