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Measurement · 3 min read

How much can you compress a PNG on a Mac?

Losslessly by 50.6% at the median, with fewer colors by 76.6%. Measured on 20 PNG screenshots on a MacBook Pro on October 19, 2026: oxipng alone made them 26.3% to 58.7% smaller, pngquant followed by oxipng 64.6% to 84.3%.

How much does lossless compression save?

Losslessly, a PNG shrank by about half at the median: across the 20 screenshots from October 19, 2026 on the MacBook Pro, oxipng saved 50.6%, taking 866 KB down to 440 KB. Text and interface saved about 51% and 52%, photos 36.8%.

oxipng is a lossless PNG optimizer, so the pixels stay the same (oxipng on GitHub, checked October 19, 2026).

How much does compression with fewer colors save?

With fewer colors, every one of the 20 screenshots got smaller than with lossless compression alone: on October 19, 2026 on the MacBook Pro, pngquant followed by oxipng saved 76.6% at the median, taking 866 KB down to 198 KB.

pngquant shrinks a PNG with lossy compression based on a newly generated color palette (pngquant.org, checked October 19, 2026).

With fewer colors, each type of content saves 25 to 34 percentage points more than with lossless compression alone.

Content PNG oxipng pngquant and oxipng
Text 704 KB 344 KB (−51.2%) 159 KB (−76.1%)
Interface 640 KB 306 KB (−52.1%) 141 KB (−79.4%)
Photo 10.29 MB 6.73 MB (−36.8%) 2.80 MB (−71.2%)

All values are medians of the 7, 7 and 6 captures in each group, with the saving against the PNG in parentheses.

How do you compress a PNG on a Mac?

With the command-line tools oxipng and pngquant, or with Levati, which runs both one after the other for PNG files; the 76.6% median comes from that sequence on the MacBook Pro on October 19, 2026.

A screenshot of a photo stays large as a PNG even afterwards: 2.80 MB at the median. As HEIC, the same group came to 519 KB at the median in the same set of captures, see Is a Mac screenshot smaller as a JPG than as a PNG?.

How was this measured?

The measurement covers 20 PNG screenshots taken on October 19, 2026 on the built-in Liquid Retina XDR display of a MacBook Pro with M5 Pro running macOS 27.0.1.

  1. Capture: for each piece of content, a Chrome window of 2056 × 1290 points with screencapture -x -o -l <window> -t png, each 4112 × 2580 pixels at 144 dpi.
  2. Content: 7 captures of text, 7 of interface, 6 of photo.
  3. Lossless: oxipng 10.2.1 with --quiet and no other options.
  4. Fewer colors: the Levati command-line tool, which runs pngquant 3.0.3 with --skip-if-larger followed by oxipng 10.2.1.
  5. Analysis: file size in bytes, median and range from minimum to maximum; 1 KB is 1,000 bytes, 1 MB is 1,000,000 bytes.

Other devices and image quality were not measured; the captures themselves are not published.