Choosing the Right File Format: A Practical Reference

Use PDF whenever the layout must not change and the recipient will not edit it — contracts, invoices, CVs, anything going to print. PDF embeds fonts and fixes positions, so the document looks the same everywhere.

Use DOCX when the recipient must edit the content and you both work in a word processor. Use plain text or Markdown for notes, documentation and anything destined for a version control system, because plain formats diff cleanly and never become unreadable.

Photographs belong in JPEG or, better, WebP. Screenshots, diagrams and anything containing text belong in PNG or WebP at high quality. Logos and icons belong in SVG whenever a vector original exists, because a two-kilobyte SVG stays crisp at every size.

Avoid converting a JPEG to PNG in the hope of improving it. The detail lost during the original JPEG encoding is gone; the PNG simply stores the same degraded pixels in a much larger file.

MP3 remains the safest audio interchange format, and 192 kbps is comfortably transparent for speech and most music. Use WAV or FLAC only for masters and editing sources, where lossless matters.

MP4 with H.264 video and AAC audio plays on essentially every device made in the last decade and is the right default for sharing. WebM is smaller for web embedding. Repeated re-encoding degrades video quickly, so always keep an original and export from it rather than from a previous export.

ZIP is the universal choice; every operating system opens it natively without extra software. Reach for 7z only when you need maximum compression and know the recipient has a suitable extractor.

Avoid RAR for sharing. It is a proprietary format and many recipients will need to install something before they can read what you sent.

Each lossy re-encode discards information permanently, so chained conversions compound damage. Converting an MP3 to WAV does not restore quality — it only stores lossy audio in a larger container.

Similarly, a PDF exported from a Word file and then converted back to Word is not the original document; it is a reconstruction. When you own the source file, always share or edit from the source rather than from a converted derivative.