Try it: compress your own text
Type or paste, or pick a file. Compression runs in your browser with gzip; nothing is uploaded.
–
Measuring…
Ratios, percentages and what can be squeezed
A compression ratio is original size ÷ compressed size. 100 MB down to 25 MB is 4:1. The saving is 1 − 1 ÷ ratio: 75 %. The two scales behave very differently. Going from 2:1 to 4:1 saves another quarter of the original; going from 10:1 to 20:1 saves only another 5 %.
Lossless compressors (zip, gzip, 7-Zip, FLAC) find repetition and predictable patterns and write them more compactly. You get back exactly the original bytes. Text, spreadsheets and logs are full of repetition and shrink 3–10 times. Photos, music and video are already compressed with lossy methods that keep only what you perceive, so zip finds almost nothing left: a folder of JPEGs zips to about the same size.
The demo above uses your browser's built-in gzip, the same DEFLATE method behind .zip files, so the ratio it shows is a real measurement on your text.
Reference
| Ratio | Size left | Saved |
|---|---|---|
| 1.1:1 | 90.9 % | 9.1 % |
| 1.25:1 | 80 % | 20 % |
| 1.5:1 | 66.7 % | 33.3 % |
| 2:1 | 50 % | 50 % |
| 3:1 | 33.3 % | 66.7 % |
| 4:1 | 25 % | 75 % |
| 5:1 | 20 % | 80 % |
| 10:1 | 10 % | 90 % |
| 20:1 | 5 % | 95 % |
| File type | Typical ratio |
|---|---|
| Plain text, CSV, logs | 3:1 – 10:1 |
| HTML, JSON, source code | 3:1 – 8:1 |
| Office documents (.docx, .xlsx) | ≈ 1:1 (already zipped inside) |
| JPEG / HEIF photos | ≈ 1:1 (1–3 % saving) |
| MP3 / AAC music | ≈ 1:1 |
| MP4 / MOV video | ≈ 1:1 |
| BMP / uncompressed TIFF | 2:1 – 4:1 |
| WAV audio | 1.1:1 – 1.3:1 with zip; ~2:1 with FLAC |