To make a PDF smaller, you can either compress it, simplify its contents, or re‑export it with lighter settings. Below are quick options for different devices and skill levels.

Super quick methods (no tech skills needed)

1. Use an online compressor

Good for: one‑off files, no software installed. Typical steps on most online tools (Adobe, Smallpdf, iLovePDF, etc.)

  1. Go to a trusted “Compress PDF” website.
  2. Upload your PDF (drag and drop or “Select file”).
  3. Pick a compression level (Low/Medium/High).
  4. Download the compressed PDF.

Pros:

  • Fast, no installation.
  • Great when you just need to email or upload something once.

Cons:

  • You’re uploading to a third party (avoid for confidential docs).
  • Higher compression can reduce image quality.

On a Mac (Preview app)

macOS has a built‑in way to shrink PDFs via Preview.

  1. Open the PDF in Preview.
  2. Click File → Export…
  3. In “Quartz Filter,” choose Reduce File Size.
  4. Save (or change the filename if you want to keep the original).

This quickly creates a lighter copy, but images may become more compressed and slightly fuzzier, especially if you print it.

With full PDF software (Adobe, PDF editors)

1. Adobe Acrobat (paid desktop)

Most PDF editors have a “Reduce File Size” or “Optimize PDF” option; Adobe Acrobat and similar tools let you:

  • Compress images (lower resolution, stronger JPEG compression).
  • Remove hidden data, comments, JavaScript, and embedded files.
  • Flatten layers and forms so the file becomes simpler.

General workflow:

  1. Open the PDF in your editor.
  2. Look for File → Save as Other → Reduced Size/Optimized PDF or an Optimize/Compress button.
  1. Choose your settings (screen‑view only vs. print‑quality).
  2. Save as a new file.

Tip: If you might need to edit or print at high quality later, keep your original file as a backup.

2. Other PDF editors (e.g., PDF Pro)

Many non‑Adobe tools also compress and “flatten” PDFs:

  • Compress to reduce size.
  • Flatten to turn interactive elements into static content so the file is simpler and smaller.

Without special tools: simple tricks

If you can edit the source (Word, PowerPoint, etc.) before exporting the PDF, you can often get a much smaller file:

  • Reduce image sizes before export : Use lower‑resolution images or compress pictures in the original document.
  • Avoid unnecessary images or huge screenshots.
  • Export as “minimum size / web” instead of “high quality / print” in your office app.

If the PDF is very long and you only need parts of it, you can also:

  • Split the PDF into several smaller PDFs (e.g., pages 1–5, 6–10, etc.). This doesn’t compress, but it makes each piece smaller for uploading to strict forms.

File compression (zipping)

You can put the PDF into a ZIP file to reduce size a bit and make sending easier:

  • On Windows: Right‑click the PDF → Send to → Compressed (zipped) folder.
  • On macOS: Right‑click → Compress.

This is handy for email/transfer, but people must unzip it before opening and size reduction may be modest.

Choosing the best method

When you’re deciding how to make a PDF smaller, think about:

  • Privacy
    • Sensitive / confidential document → prefer local tools (Preview, Adobe, desktop apps).
    • Non‑sensitive → online compressors are fine.
  • Quality needs
    • Just for on‑screen reading or upload to a web form → medium or strong compression is usually OK.
* For high‑quality printing → use milder compression or an “optimized” setting that preserves more image detail.
  • Speed vs. control
    • Fastest: Quick online compressor or Preview’s “Reduce File Size.”
* Most control: Full PDF editor where you can tune image resolution and remove hidden objects.

TL;DR: For most people, the easiest path is: open an online “Compress PDF” tool, upload, pick a compression level, and download the new file; Mac users can also use Preview’s “Reduce File Size” export to shrink PDFs locally.

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