What file format should I use for long-term electronic records?

There is no single “correct” file format for every long-term electronic record. The better question is which format characteristics give a record the best chance of remaining accessible, readable, and trustworthy years or decades from now. The guiding principle is to favor open, well-documented, widely adopted, standards-based formats over proprietary or rapidly changing ones.

What makes a format suitable for long-term retention

When evaluating a format, look for these qualities:

• Open and documented: The specification is public, so the format can be read even if the original software disappears.
• Widely adopted: Common formats are more likely to be supported by future tools.
• Non-proprietary and unencrypted: Avoid formats locked to a single vendor, and store records without password protection or DRM that could block future access.
• Stable and self-contained: The format changes slowly and does not rely on external links, fonts, or plug-ins to render correctly.
• Lossless where fidelity matters: For images and audio, prefer formats that preserve original quality rather than discarding data.

Commonly recommended format families

These categories are widely used in digital preservation practice:

• Documents and text: PDF/A (an archival profile of PDF) and plain text or open document formats.
• Images: TIFF or PNG for high-fidelity needs; JPEG 2000 for some archival imaging.
• Spreadsheets and data: CSV or other open, delimited formats for tabular data.
• Audio and video: Open, well-supported container and codec combinations chosen for stability.

Format is only part of the answer

A durable format does not preserve a record by itself. You also need to capture and protect metadata (context, dates, authorship) and fixity information so you can prove the record has not changed. Plan for format migration over time, monitor for obsolescence, and store multiple copies with integrity checks. Always align format choices with your retention schedule and any legal or regulatory requirements for the record series.

For more guidance, explore the electronic records topic hub.