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Compression Ratio Calculator

Ratio, percent reduction, and savings.

Compression ratio
2.86:1
65.0% smaller · saves 65.00 MB
Original: 100 MB
Compressed: 35 MB
Reduction: 65.00%
Space factor: 35.00% of original

Typical ratios

  • JPEG photos: 5–10:1 lossy
  • PNG images: 2–5:1 lossless
  • MP3 audio: 10–12:1 lossy
  • FLAC audio: 1.5–2:1 lossless
  • H.264 video: 50–100:1
  • Brotli text: 3–5:1
  • gzip text: 2.5–4:1
  • zstd text: 3–5:1

Compression ratio = original / compressed. A 4:1 ratio means the compressed file is 1/4 the size, or 75% smaller. Different formats are designed for different content; trying to gzip a JPEG barely helps because JPEG is already compressed.

About

Enter original and compressed file sizes. Get the compression ratio (e.g. 4:1), the percent reduction, and absolute savings. Includes typical ratios for common formats (JPEG, MP3, gzip, brotli).

How to use

  1. Enter original and compressed sizes.
  2. Read ratio and percent.

FAQ

Why doesn't gzipping a JPEG help?+

JPEG already compresses image data. gzip works on text patterns; JPEG output looks like random noise to it. The order matters too: compress the original raw data once with the right tool.