How to Compress a PDF for Outlook
Outlook and Microsoft 365 typically block attachments over 20 MB, and some company servers set the bar even lower.
Open the Compress PDF toolA heavy PDF — especially a scan or a deck full of images — easily trips that limit. Compressing it lets you send the document through Outlook without resorting to OneDrive links or a zip workaround.
Compress your file here, then attach the smaller copy to your Outlook message.
Steps to Compress a PDF for Outlook
Upload your PDF
Drag the file into the tool or click to browse. It loads instantly in your browser.
Pick a compression level
Choose light, balanced, or strong compression depending on how small you need the file.
Download the smaller PDF
Save the compressed file in one click — ready to attach, upload, or submit.
Keeps text sharp
Smart compression strips redundant data and recompresses images without making text fuzzy.
100% private
Everything happens in your browser. Your files are never uploaded to a server, so nothing is stored, shared, or seen by anyone but you.
Free, no sign-up
No account, no watermark, and no install. Use it as many times as you need, completely free.
Ready to start?
Compress PDF runs free in your browser — your files never leave your device.
Open Compress PDFFrequently asked questions
What is Outlook's attachment size limit?+
Outlook.com and most Microsoft 365 setups cap attachments at 20 MB, though individual organizations can lower it. Compressing under 10 MB avoids almost all of these limits.
Will compressing reduce the quality of my PDF?+
Text stays crisp because it is vector-based. Image-heavy pages are recompressed, and you control how aggressive that is with the compression level.
Is there a file size limit?+
The tool runs in your browser, so it comfortably handles typical documents. Very large scans may take a few extra seconds to process.