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How to Compress PDF on Mac: 3 Methods

Compress PDF on Mac with GetCompress, Preview Reduce File Size, or a Keynote re-export. Shrink decks and scans for email and portals.

By Petr Samokhin

A 40-slide deck can be 30 MB even when the text is light. Embedded images carry the weight. Email bounces and portals reject uploads long before anyone reads the content.

Three solid routes cover most Mac jobs: GetCompress for batches and presets, Preview for one file, and a fresh export from Keynote or PowerPoint when you still have the deck.

Method 1: GetCompress

Best for: Folders of decks, scans, and reports that share the same optimization every week. Local processing matters for contracts and unreleased materials.

GetCompress PDF settings with compression and image optimization options
  1. Open GetCompress and drop one PDF or a folder into the queue.
  2. Pick a PDF compression preset. GetCompress optimizes embedded images inside the file.
  3. Preview a chart-heavy or signature page when small type matters.
  4. Export a new copy; keep the master.

Save the preset so the next compress pass is one click. PDF compression does not use an exact megabyte target file size. That control is video-only. Use quality and image optimization, then check Finder size against your email or portal limit.

Method 2: Preview Reduce File Size

Best for: One PDF without extra installs.

  1. Open the PDF in Preview.
  2. File → Export…
  3. Set Quartz Filter → Reduce File Size.
  4. Save as a new file and zoom charts, small type, and signature lines.

If text looks muddy, stop and re-export from the source deck instead of filtering harder.

Optional Ghostscript via Homebrew when you want an /ebook profile:

brew install ghostscript
gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook \
 -dNOPAUSE -dQUIET -dBATCH -sOutputFile=compressed.pdf input.pdf

Limitation: One file at a time. Aggressive filters can soften type that was already borderline.

Method 3: Re-export from Keynote or PowerPoint

Best for: Decks you still have as KEY or PPTX.

  1. Open the source in Keynote or PowerPoint.
  2. Export PDF at screen image quality, not print.
  3. Compare one chart-heavy slide before you send the full deck.

Exporting near 1280 or 1920 px wide is usually enough for laptops and projectors. Keep a print-quality archive separate from the email copy.

When the PDF came from scans rather than slides, merge carefully first: JPG to PDF on Mac . For page images instead of one document, see PDF to images on Mac .

Limitation: Needs the editable source. Vendor PDFs without a deck skip this method.

Which method should you use

SituationStart here
Folder of PDFs, recurring preset, local-onlyGetCompress
One contract or invoicePreview
You still have the Keynote or PowerPoint fileRe-export
DestinationTypical limitPractical starting point
Corporate email10 to 25 MBAim under 8 MB for headroom
Web portals5 to 20 MBCompress before upload; keep a master
Print shopsOften no strict capSend the uncompressed master

Limits change by plan. Treat the table as planning ranges.

Why PDFs get large

Most bloat is raster images saved at print resolution inside a file meant for screens. Text and vectors stay small; photos, slide bitmaps, and scans dominate.

PDF typeUsual causeTry first
Exported slidesFull-size image per slideRe-export at screen quality
ScansHigh DPI on every pageRe-scan at 150 to 200 DPI, or compress
Photo insertsLarge JPEG embeddedOptimize images, then check charts

If you merge many JPEG scans, compress after merge. Each photo can look fine alone and still blow the attachment limit together.

When Preview is enough

Preview can finish one file when Reduce File Size clears the limit and text stays sharp.

GetCompress also works well for that job. It also covers quarterly report folders, scan batches, the same preset, or sensitive files you will not upload to a browser tool. It does not replace Keynote. For broader cleanup, see reduce file size on Mac .

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