Best File Formats for Backing Up

Introduction

Creating backups is about two things: fidelity (how well the backup preserves your data) and recoverability (how easily you can restore it later). Choosing the right file format affects both. Some formats are ideal for long-term archival; others are optimized for small size or speed. This guide explains the best choices, explains why they matter, and gives concrete recommendations for different types of data.

General principles

When picking backup formats, favor open or widely supported formats, prioritize lossless storage for primary backups, and keep at least two independent copies on separate media or services. For critical assets, preserve metadata (timestamps, authorship, EXIF for photos), keep checksums, and avoid single-vendor lock-in where possible. Always encrypt sensitive backups and never store passwords or login credentials in plain text inside a backup file.

Documents (text, reports, ebooks)

For text-heavy documents, choose formats that preserve layout and are likely to be readable decades from now.

• PDF/A — the archival variant of PDF. Use PDF/A for final, print-ready documents. It embeds fonts and prevents external dependencies.
• DOCX / ODT — modern editable formats. Keep source files in DOCX (widely supported) or ODT (open standard). For long-term archives, export to PDF/A as well.
• Plain text (UTF-8) — for code, scripts, and data exports, use UTF-8 plain text files and include a README describing encoding and structure.

Images and graphics

Your choice depends on whether you need lossless fidelity or small size.

• TIFF (uncompressed or lossless) — excellent for archiving master images, scans, and graphics that must not lose quality. TIFF supports multiple pages and metadata.
• PNG — lossless and broadly supported; great for screenshots, diagrams, and images with transparency.
• JPEG (high quality) or JPEG 2000 — use for photographic images when storage is tight; avoid excessive recompression. For archival, prefer TIFF or PNG.
• RAW — if preserving camera originals, keep vendor RAW files (CR2, NEF, ARW) alongside a converted TIFF/PNG master.

Audio

Audio also divides into masters (highest quality) and distribution copies.

• WAV (lossless PCM) — standard archival choice for uncompressed audio masters.
• FLAC — lossless compressed alternative; smaller than WAV but fully reversible.
• MP3 / AAC — use only for distribution copies where size matters; do not rely on lossy formats alone for archives.

Video

Videos take a lot of space. Preserve a master copy and then create compressed derivatives for playback.

• MKV/MP4 (H.264/HEVC) — widely playable containers for compressed video. For archival masters, consider lossless or high-bitrate formats if storage allows.
• ProRes / DNxHD — professional codecs for editing and preservation; large but high-quality.

Databases and structured data

Back up database dumps in native, portable formats that can be re-imported and audited.

• SQL dump (UTF-8) — for relational databases, an SQL export is portable and human readable.
• CSV/TSV — for tabular data export; accompany with a schema or README documenting field types and encodings.
• NDJSON / JSON Lines — for structured log-like exports. For richer schemas, JSON or XML with a schema file is appropriate.

Archives and containers

Use archive containers to group many files, preserve permissions, and compress where appropriate.

• ZIP — ubiquitous and convenient, but historically has had metadata/permission limitations on Unix systems. Use for cross-platform convenience.
• 7z — better compression than ZIP, open source, supports modern encryption; great for long-term compressed archives.
• tar + gzip / xz — standard on Unix/Linux. Use tar.gz or tar.xz to preserve permissions and metadata. For very large archives, prefer tar.xz or segmented archives.

Emails

For email backups, export in formats that preserve headers and attachments.

• MBOX — a common mailbox format that stores messages sequentially and is importable by many clients.
• EML — one file per message; good for selective archiving and indexing.

Checksums, verification & integrity

Always generate and store checksums (SHA-256 or better) alongside backups. Checksums let you detect bit rot or transmission errors. Keep a text file listing filenames, sizes, timestamps, and checksums. For extra assurance, run periodic integrity checks to confirm your backups remain unchanged.

Encryption and sensitive credentials

Never store plaintext passwords, API keys, or login credentials inside a backup file. For services like "Uphold" or any financial account, do not place usernames/passwords in a general backup. Instead:

• Use a dedicated password manager (export its encrypted backup format) to store credentials securely.
• If you must back up secrets, export them into an encrypted archive (7z with AES-256 or a GPG-encrypted file) and store the passphrase separately from the archive location.

Versioning and incremental backups

Rather than overwriting a single backup file, store versioned copies (daily snapshots, weekly, monthly). For large datasets, use incremental/differential backups — tools like rsync, Borg, Restic, or commercial snapshot systems let you store only changed blocks or files while keeping access to earlier versions. Ensure your backup tool supports your chosen archive formats or export pipelines.

Practical workflow & checklist

A simple reliable workflow:

1. Create master copies in lossless/open formats (PDF/A, TIFF, FLAC, WAV, SQL, RAW).
2. Export convenient editable versions (DOCX, ODT, PNG, JPG high-quality) for day-to-day use.
3. Archive with container + checksum (e.g., project-2025-10-10.7z + project-2025-10-10.sha256).
4. Encrypt backups containing sensitive data with strong encryption (GPG or 7z AES-256).
5. Store at least two copies: one offline (external drive, cold storage) and one offsite (cloud / another geographic location).
6. Document the restore procedure and perform periodic test restores (don’t assume backups work until you’ve restored them at least once).

Long-term archival considerations

For digital preservation over decades, prefer open standards (PDF/A, TIFF, ODF, plain text, PNG, FLAC) and avoid proprietary formats that may lose support. Keep migration plans: every few years, verify the formats and migrate masters if a format is becoming obsolete.

Summary recommendations (quick reference)

• Documents: PDF/A for archival, DOCX/ODT for editable sources.
• Images: TIFF/PNG for masters, JPEG for distribution.
• Audio: WAV/FLAC for masters, MP3 for distribution.
• Video: ProRes/DNxHD for masters, MP4/H.264 or MKV for distribution.
• Databases: SQL dumps (UTF-8), CSV/JSON exports with schema.
• Archives: 7z or tar.xz for compression; ZIP for maximum cross-platform convenience.
• Security: SHA-256 checksums + GPG or AES-256 encryption for sensitive backups.

Final notes

Choosing the right formats is only one part of a reliable backup strategy. Combine good format choices with redundancy, periodic integrity checks, documented restore instructions, and sound security practices. If you follow the recommendations above you’ll maximize the longevity and usefulness of your backups while minimizing the risk of data loss or vendor lock-in.