What Is a UDF File?

How to open, edit, and convert UDF files

What to Know

This article describes the various formats that use the UDF file extension, how to open each type, and how to save each format to one that uses a different file extension, like ISO, MP4, AVI, or CSV.

What Is a UDF File?

A file with the UDF file extension is most likely either a Universal Disk Format file or an Excel User Defined Function file.

UDF is a common file system used by optical media burning programs to store files on discs, so the actual UDF file extension (.UDF) might not be as prevalent. Instead, even though the program that does the burning will do so using the UDF standard, it most likely associates the file with itself by appending a different file extension to the end of the file name.

Some UDF files may instead be Excel User Defined Functions created by Microsoft Excel that will execute certain predefined functions when opened. Others could be Ricoh address books that hold user information.

Screenshot of UDF files in Windows 10

UDF is also short for some unrelated technology terms like uniqueness database file, user-defined feature, user-defined font, and ultra-deep field.

How to Open a UDF File

Universal Disk Format files that have the UDF extension can be opened using Nero or with a free file unzip utility like PeaZip or 7-Zip.

UDF scripts that are Excel User Defined Functions are created and used by Microsoft Excel via its built-in Microsoft Visual Basic for Applications tool. This is accessible through the Alt+F11 shortcut in Excel but the actual script content probably doesn't exist with the .UDF file extension, but is instead stored within Excel.

UDF files that are Ricoh address book files require the discontinued SmartDeviceMonitor for Admin software from Ricoh. You might be able to open it with their newer Device Manager NX Lite tool but the older SmartDeviceMonitor for Admin is still available.

Another way to open this file is to use Notepad or another text editor. Many files are text-only files meaning no matter the file extension, a text editor may be able to properly display the file's contents. This may or may not be the case with UDF files but it's worth a try.

UDF files in MS Excel have the potential to store malicious scripts. Take great care when opening executable file formats like this that you've received via email or downloaded from websites you're not familiar with. See our List of Executable File Extensions for a listing of file extensions to avoid and why.

How to Convert a UDF File

While the UDF format is widely used for storing data on discs, converting the file format to a media file format is not how you want to go about this. For example, if you want to "convert" UDF to MP4 or ISO, it's best to use a video file converter or a DVD ripping program.

Consider a disc that you want to be saved as an ISO or in a video format like MPEG. The best way to get this done if you need the data in the ISO format is to use a program like BurnAware.

Need your UDF content to be in a video file format? You can rip the content off of a disc and store it in a playable format like MP4 or AVI using a program like Freemake Video Converter.

To convert UDF to CSV, if you have a Ricoh address book file, requires the SmartDeviceMonitor for Admin software from Ricoh. As mentioned above, that software is no longer available from that company but you might be able to use it normally from the download link above, or with Device Manager NX Lite.

If you're looking for a file system converter that can convert UDF to NTFS or FAT32, for example, try formatting the partition with Disk Management. Keep in mind that some devices will not support every possible file system.

Still Can't Open Your File?

If your file doesn't open as described above, then it's most likely not a Universal Disk Format file or an Excel User Defined Function file. Instead, you probably have something that doesn't even end in UDF.

For example, the PDF format is really popular and is spelled in almost the exact same way as UDF. However, PDF files can't open with UDF openers, and neither can a UDF file be used with a PDF viewer.

The same concept applies to many other formats and extensions, like UD files that are OmniPage User Dictionary files used with the OmniPage software; DAZ User files that use the DUF suffix; and MagicISO's Universal Image Format that utilizes the UIF file extension.

The point here is to double-check the file extension. There's a good chance that you're dealing with a similarly spelled, but entirely different file format that should be treated as such. Research the extension of your specific file to find which programs can open or convert it.