Choosing Archive-Friendly File Formats

Saving a file is only half the job; the other half is making sure software will still understand it years from now. Formats come and go. Some are used by every device on earth, while others depend on a single program that may stop being maintained. When you choose formats for files you want to keep, you are really choosing how likely a future reader is to open them.

What Makes a Format Durable

Archivists look for a few common traits:

Openly documented. If the specification is public, anyone can write software to read it, even if the original program disappears.
Widely adopted. A format used by many programs and platforms is more likely to be supported for a long time.
Not tied to one product. Files that need a specific application or version are riskier.
Uncompressed or lossless when practical. Fewer layers of processing mean less can go wrong, and nothing is thrown away.
Self-contained. Files that embed their fonts, images and settings are easier to open later than those depending on outside resources.

No format is guaranteed to last forever, and experts disagree about details. Treat these traits as a way of reducing risk, not eliminating it.

Text and Documents

For plain notes and records, simple text files are about as durable as it gets, because almost any program can read them. For formatted documents, widely supported formats such as PDF have long been popular for final versions. A special archival flavor of PDF exists for long-term preservation, which we discuss in a separate article. Keep editable working versions in a common open document format as well, in case you need to change the text later.

Photos

For everyday photos, JPG is extremely well supported and a practical choice. For important images, many people keep an uncompressed or lossless version too, such as TIFF or PNG, since these retain every detail. Camera makers' raw formats hold the most information, but they vary by brand and model, so keep a more common copy alongside them.

Audio and Video

For audio, lossless formats preserve everything the recording captured, while compressed formats trade some detail for smaller size. A reasonable approach is to keep a lossless master of valuable recordings and use compressed copies for listening.

Video is harder, because files are large and formats depend on codecs, the methods used to encode them. Mainstream, widely supported combinations are the safest bet. For precious home videos, keep the highest-quality original you have, and consider making a compatible copy for everyday viewing.

Spreadsheets, Databases and Specialized Files

For spreadsheets, a plain comma-separated text export keeps the raw data readable almost anywhere, although formulas and formatting will not survive. Keep the original file too. For specialized or proprietary files, such as design or accounting data, export to an open or common format when possible, and keep notes about the program and version that created the original.

Keep Originals and Add Safer Copies

A useful rule is to keep the original file as created and also store a copy in a more durable format. The original may carry details that conversion loses, and the copy gives you a fallback if the program fades away. Label them clearly, for example by adding the word original or archive to the file name, so you can tell which is which.

Review Formats Now and Then

Once a year, think about whether any formats in your archive have become hard to open. If a program has stopped working on your newer computer, convert those files soon, while a way still exists.

Frequently Asked Questions

Is PDF a good archival format? For final documents it is a strong choice, particularly the archival variant. Keep editable originals separately.

Should I convert everything right away? No. Prioritize files in formats that depend on aging or obscure software, and keep originals when you convert.

Are cloud-native formats safe for long-term keeping? Documents that live only inside an online application depend on that service. Export copies to standard formats and store them yourself.