15 File Compression Tips That Actually Work

Compression is part science, part good habits. These 15 tips — across images, PDFs, video and archives — will help you make files dramatically smaller without wrecking them.

Universal habits

1. Always keep the original. Compress a copy; re-compressing the same lossy file repeatedly stacks quality loss.
2. Match format to content before touching any quality slider — the wrong format is the biggest hidden cost.
3. Right-size before compressing. Fewer pixels/lower resolution beats aggressive quality cuts almost every time.
4. Judge by preview, not by number. A file-size figure tells you nothing about whether it still looks good.

Images

5. Photos → JPG or WebP at quality ~80; graphics → PNG or lossless WebP. (Format guide.)
6. Use WebP or AVIF for the web — 25%+ smaller than JPG/PNG.
7. Quantize PNGs (reduce colors) to keep transparency while shrinking — how-to.
8. Need an exact size? Use target-size mode instead of guessing.

PDFs

9. The images are the weight — downsample them to ~150 DPI for screen use.
10. Text stays sharp regardless, because it's vector data. (More.)
11. Grayscale documents that don't need color.

Video

12. Use CRF encoding (~23) rather than a forced bitrate.
13. Downscale to the resolution it'll actually be viewed at.
14. Modern codec (H.265/VP9) for ~30–50% smaller files where supported. (Guide.)

Archives

15. Don't ZIP already-compressed files (JPG, MP4, MP3) expecting big gains — they're already dense. ZIP shines on text, code and documents.

Put them to work

Most of these start with a well-compressed image — exactly what the free FreeCompressor image tool produces in your browser. For the theory tying it together, read the complete guide to file compression.