You can reduce PDF file size either with built‑in tools on your device or with online compressors, while balancing size vs. quality.

Fast methods on any device

  • Use an online compressor (easiest, no install):
    • Go to a trusted site like Adobe’s free Compress PDF tool or Smallpdf’s compressor.
* Upload your PDF.
* Choose compression level (often “basic/medium” vs “strong/high”).
* Download the smaller file.
  • Typical results:
    • Basic compression keeps good readability and is fine for email or web uploads.
* Strong compression is useful if you must meet strict limits (for example, under 1 MB) but may slightly blur images or fine text.

Windows/macOS with Adobe Acrobat Pro

If you have Acrobat Pro (not just the free Reader), it has built‑in optimizers.

Simple one‑click shrink

  1. Open the PDF in Acrobat Pro.
  2. Open the “Optimize PDF” or “Compress PDF / Reduce File Size” tool.
  1. Click Reduce File Size.
  2. Choose the compatibility level (for example, keep compatibility with older Acrobat versions).
  3. Save as a new file so you still have the original.

Advanced control with PDF Optimizer

  1. In Acrobat Pro, choose File → Save as Other → Optimized PDF.
  1. Click Audit space usage to see which parts (images, fonts, etc.) are largest.
  1. Lower image resolution and compression where needed, or remove unnecessary items.
  2. Save as a new file.

This lets you target the real “space hogs” instead of blindly compressing everything.

macOS built‑in options (Preview)

On a Mac, you can compress without extra apps.

  1. Open the PDF in Preview.
  2. Go to File → Export.
  3. In “Quartz Filter,” choose something like “Reduce File Size” or “Shrink PDF.”
  1. Save as a new file.

This is quick and works well for everyday documents, though it can make photos look softer.

Other desktop tricks (any OS)

Even without Acrobat Pro, there are ways to shrink PDFs while you’re creating or editing them.

  • Re‑“print” to PDF with smaller settings
    • From your original app (Word, PowerPoint, etc.), choose Print → PDF printer.
    • Select a preset like “Smallest file size” or “Web” quality.
* This strips extra metadata and heavy print‑quality images.
  • Use “Save As” instead of “Save” in your PDF editor
    • Some editors rebuild the internal structure and remove hidden clutter when you do a fresh “Save As,” which can noticeably cut size.
  • Lower image resolution before making the PDF
    • If your document is heavy on photos, compress or resize the images first in an image editor.
    • Then recreate the PDF. This often yields much smaller files with acceptable quality for screens.

When normal compression isn’t enough

Sometimes portals enforce strict limits (e.g., under 1 MB or even under 500 KB).

  • Try “strong” or “maximum” compression settings in an online tool like Smallpdf and set a target size if the tool allows.
  • If it’s still too large:
    • Remove non‑essential pages, big images, or attachments.
    • Split the PDF into multiple smaller PDFs (for example, pages 1–5, 6–10, etc.) when allowed.

Simple strategy to follow

  1. Start with a free online compressor.
  2. If you need more control, use Acrobat Pro’s Optimize/Reduce File Size tools.
  1. On Mac, use Preview’s “Export → Reduce File Size.”
  1. For very tight limits, combine strong compression with trimming pages or images, or splitting the file.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.