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Compress PNG on Mac: 3 Methods

Compress PNG on Mac with GetCompress, Preview, or oxipng. Resize first, then lossless recompress screenshots without losing transparency.

By Petr Samokhin

A Figma export at 2880 px wide lands in Slack as an 8 MB PNG. The message sends, but the thread crawls on mobile data and the next upload form rejects the same file. PNG is right for UI with transparency, yet full-monitor exports are almost never viewed at that size. Resize first, then lossless recompress, or change format when alpha is not required.

Three solid routes cover most Mac jobs: GetCompress for recurring batches, Preview for one or a few files, and sips plus oxipng in Terminal.

Method 1: GetCompress

Best for: One file or folders of PNG screenshots (often mixed with JPEG or HEIC) with a max-width preset you reuse often.

GetCompress main window with images queued and image settings open, including max width and format options
  1. Open GetCompress and drop PNG files or a folder into the queue.
  2. Set max width and keep PNG when transparency matters.
  3. Preview icon edges and small type, then export.
  4. Convert to WebP or JPEG in the same pass when alpha is no longer needed.

Processing stays on your Mac. Exact target file size applies to video only, not images.

Method 2: Resize in Preview

Best for: One or a few PNG files.

  1. Open the PNG in Preview.
  2. Tools → Adjust Size… and set width (for example 1920 for a hero, 1280 for a deck slide).
  3. File → Export… and keep PNG if transparency matters.
  4. Save as a new file and compare size in Finder.

Zoom on small type, icon edges, and semi-transparent overlays. If the image is a photo without alpha, export as JPEG at quality 85 instead and keep the original PNG archived.

Limitation: No reusable preset across a full mockup folder.

Method 3: sips and oxipng in Terminal

Best for: Same max width across a folder, plus lossless bitstream savings after resize.

brew install oxipng
mkdir out
for f in *.png; do sips -Z 1920 "$f" --out "out/$f"; done
cd out
for f in *.png; do oxipng -o 4 --strip safe "$f"; done

--strip safe removes non-critical metadata while keeping useful color profiles. Run oxipng on the resized file, not on a 4000 px original you plan to shrink later. Feeding a photo PNG through oxipng alone rarely fixes bloat when dimensions stay oversized.

Limitation: No saved presets. Mixed formats still need separate steps or a dedicated app.

Which method should you use

SituationStart here
Recurring design file folders, mixed formats, presetsGetCompress
One screenshotPreview
Scripted resize plus lossless passsips + oxipng

Broader advice: how to compress images on Mac . Web delivery: PNG to WebP on Mac . Keep client mockups local ( are online file compressors safe ).

Lossless vs lossy choices

PNG compression is lossless by default: every pixel survives re-save. You still shrink files by resizing, rewriting the bitstream, or converting when transparency does not matter.

ApproachBest when
Resize pixelsImage displays smaller on screen
Lossless PNG toolsTransparency must stay; UI stays sharp
WebP or JPEGNo alpha; photos and heroes for web
Lower color depthFlat UI with few distinct colors

Read lossy vs lossless compression before you convert a screenshot to JPEG and lose crisp edges. Compare one representative file with the image comparison tool .

When Preview or Terminal is enough

Preview can finish a single resize. Terminal can work when the folder is uniform and your README already documents width and oxipng flags.

GetCompress also helps when the same max width returns every week, when PNG and JPEG arrive together, or when folder monitoring should catch new Figma drops. It does not replace a design tool. Write max width in the project README so you do not put back 2880 px files.

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