Compress PDF to 20MB for Outlook
Use the Outlook 20MB preset to stay under common email limits. PDFThin optimizes first; if it still will not fit, we split into attachment-ready parts.
Fit-or-split result: get one PDF that fits, or a ZIP of parts under the limit.
Email presets: Gmail 25MB, Outlook 20MB, Outlook.com 25MB, plus custom size.
Private by default: files auto-delete after 60 hours; we don't store document contents in logs.
How it works
Upload
Pick a PDF and a target limit.
Process
We optimize and split as needed.
Share
Download a single file or parts.
Outlook 20MB FAQ
Should I aim for 20MB or 25MB?
20MB is the safer target for internet email and mixed Outlook environments. Use 25MB if you know your mailbox allows it. You can also use the 25MB preset.
Where can I check other limits?
See email attachment size limits for Gmail, Outlook, and Outlook.com.
Outlook-friendly attachments
Why 20MB is the safe Outlook target
Many Outlook accounts and corporate mail servers cap attachments around 20 MB. Outlook.com often allows 25 MB, but the smaller target is safer for internet email and mixed environments.
Encoding overhead can add several percent to the file size, so a PDF that appears under the limit can still exceed it during delivery. Leaving headroom reduces bounce backs.
How PDFThin makes Outlook-friendly files
We remove structural bloat and optimize images without changing page layout or text flow. This often brings files under the limit with no visible change.
If the PDF still exceeds 20 MB, we split it into ordered parts that each meet the limit. You get a ZIP and can attach each part in separate emails.
When to use custom limits
If your organization sets a lower cap, choose a custom MB target. PDFThin uses the same optimize-then-split flow, just with your number.
Need a slightly larger file? Try the 25 MB preset or visit the email-ready page to pick Gmail or Outlook.com limits.
Outlook resources
See the Outlook attachment limit guide for common limits.
If a single file still will not fit, use split by size to create parts under 20 MB.
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