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Homepage / Why should we care about file formats?

Why should we care about file formats?


Darth Vader model destroying a floppy disk

Many funders require you to share your research data after your project, to increase its value and reach, and potentially increase your impact – and secure preservation makes your data easier to retrieve and understand if you want to reuse it yourself in future, too. But if data is preserved for a decade or more, how likely is it that it will actually be usable in the future?

We used to store data on DV tapes and floppy disks, but how many people could read these today? My remaining floppy disks certainly make more effective drinks coasters than storage devices! In a similar way to how physical storage formats change, file formats change, too, especially those created by companies that then go on to develop new formats or even go out of business. It’s therefore important to choose file formats wisely.

Wherever possible, you should save in an open format (such as csv), rather than a proprietary format (such as xls) that requires specific software to read it properly and is unlikely to be as interoperable. Some proprietary software only runs on particular operating systems, which excludes some users from being able to open the files. Such proprietary formats might not even be fully readable by the same software a few versions down the line – Matlab and Microsoft products in particular are known to have this issue. (Microsoft Works was discontinued in 2009 but files need to be converted to be readable today and may lose their formatting or some content in the process; have you also encountered Compatibility Mode issues in Word due to version changes?)

So to help keep your data usable for the long-term, try to choose from an open format in the table below; the more extensive UK Data Service format advice is also a valuable reference.

Type of data Recommended format(s) Format(s) to avoid
Qualitative textual data .xml, .rtf, .txt, .pdf (PDF/A) .doc
Quantitative tabular data .por, .csv, .tab .xls and other proprietary database formats
Images .tif, .png, .svg, .jpg .psd
Audio .flac, .wav .wma, .ra, .ram
Video .mp4 .wmv, .mov, .avi

If you’re depositing the file in CORD, our new data repository, we will accept all formats at the moment but are reviewing how to handle these in order to ensure the files’ long-term usability, as we are required to retain data accessibly for 10+ years. And of course sometimes you cannot avoid using a proprietary format – this is fine, but it will be important to make this clear when depositing the file on CORD or another repository, so anyone viewing the record will know what requirements there are to be able to access the data in the file. See the RDM intranet site for more advice and contact details for further help.


Image: “I find your lack of space disturbing” by N. Hussein, CC-BY-NC-SA 2.0, available at:

Written By: Georgina Parsons

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