Should you compress a large file before sending it?
By the WispFile team · Updated 24 September 2026
Compress text, spreadsheets, raw data and some design files; do not bother with video, photos, music or existing archives, which are already compressed. Compressing a video can take minutes and save almost nothing. If size limits are the only reason to compress, sending directly with no limit may be quicker.
Key facts
- Already compressed: MP4, MOV (H.264/H.265), JPEG, HEIC, MP3, ZIP, most PDFs.
- Often shrink a lot: CSV, logs, databases, uncompressed TIFF, some CAD.
- Re-encoding video to shrink it loses quality; zipping does not, but barely helps.
- You can send folders without zipping them.
What compresses
| File type | Zip helps? | Instead |
|---|---|---|
| Text, CSV, logs, JSON | A lot | Zip, or 7z for more |
| Databases, raw exports | A lot | Zip |
| PSD, uncompressed TIFF | Some | Zip if near a limit |
| Little | Send as is | |
| JPEG, HEIC, RAW | Almost none | Send as is |
| MP4, MOV, MKV | Almost none | Send as is |
| ZIP, 7z, DMG, ISO | None | Send as is |
Skip the step altogether
If you are compressing only to fit under a size limit, a direct transfer has none. Folders can be sent as they are; see sending a folder without zipping.
Frequently asked questions
How do I make a video smaller to send?
Only by re-encoding it at a lower bitrate or resolution, which loses quality. To send it at full quality, send it without compressing.
Is 7z better than zip?
It usually compresses text and data further, but the receiver needs software to open it. Zip opens everywhere.
Does compressing make sending safer?
Not by itself. Use an end-to-end encrypted link, with a password for sensitive files.
Related guides
- How to send a folder without zipping it — Keep the folder structure without the zip step.
- Email attachment too large? How to send it anyway — What to do when email says the file is too big.
- How long does it take to upload a large file? — A table of upload times, and the formula behind it.
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