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How to compress a PDF under 25MB for Outlook

Shrink a PDF blocked by Outlook or Office 365 attachment limits. Compress scan-heavy files in your browser, then proofread the output—exactly what office workers ask when email rejects a 30–40MB PDF.

Open Compress PDF ↗

What people are asking

r/Office365 (“PDF slightly too big and gets blocked”), r/pdf (“email a PDF larger than 25MB”), Facebook immigration and admin groups compressing bank statements and ADRs for uploads.

The pain is almost always a scan-heavy deck or return that is “just a little” over the cap.

What Compress PDF actually does

  • Recompress page images with quality presets aimed at email/portal caps.
  • Batch-compress multiple PDFs into a ZIP.
  • Keep processing in the browser (no upload for compression).

What it does not do

  • Guarantee every file lands under 25MB—vector/font-heavy PDFs shrink less than scans.
  • Replace a portal that rejects on page count or dimensions rather than megabytes.

Steps

  1. Open Compress PDF.
  2. Drop in the oversized PDF.
  3. Start with the email or balanced preset.
  4. Check the new file size against your limit (often ~20–25MB for Outlook tenants).
  5. Proofread: zoom signatures and fine print (Facebook designers warn online compressors can drop lines—always verify).
  6. If still too large, try a stronger preset or split into allowed chunks.

Related guides

Compress without uploading · Shrink a PDF to email · Reduce PDF file size

Go deeper

Scenario guides hub · Open Compress PDF · All PDF tools · Privacy

Last updated 2026-08-20 · Research-backed long-tail