Compress PDF for Email

Email attachment limits in 2026

The headline numbers are generous — Gmail accepts 25MB per message, Outlook.com around 20MB — but the number that matters is the smallest limit in the chain. Corporate mail servers commonly enforce 10MB, some as low as 5MB, and the recipient's provider applies its own cap on top. Attachments are also base64-encoded in transit, which inflates them by about a third. In practice, anything comfortably under 10MB, and ideally under 5MB, avoids the dreaded bounce.

How small should you aim?

Do not aim for the limit — aim well under it. A 9.5MB file against a 10MB cap can still bounce once encoding overhead and the message body are counted. The tool above shows the exact after-size on each result card, so you can verify the margin instead of hoping. If the result lands under 5MB, you are safe essentially everywhere; see also compress PDF to 5MB.

What if it is still too big?

First, check whether the recipient needs the whole document. Contracts, reports and manuals are often sent whole out of habit when two pages would do — extract the pages you actually need and the size problem often disappears. For long documents that must go whole, split the PDF into parts and send them as separate attachments. As a last resort, a file-sharing link beats a bounced email every time.

Private by design

Email attachments are often the most sensitive files people handle — contracts, medical forms, financial statements. This compressor never uploads your PDF; the re-save happens locally in your browser tab via pdf-lib. The file that gets attached is the file you downloaded, and no copy ever sat on a server in between. That also means there is no queue and no waiting: even a 20MB file processes in seconds on a modern laptop.

Frequently asked questions

What are the Gmail and Outlook attachment limits?

Gmail allows up to 25MB per message including the message itself; Outlook.com is similar at around 20–25MB. But corporate Exchange servers often enforce 10MB, and the recipient's server has its own limit too.

How small should I aim for?

Aim well under the limit — around half is comfortable. A 5MB file sails through a 10MB limit; a 9.8MB file is asking for a bounce.

What if the compressed file is still too big?

Extract only the pages the recipient needs with our <a href="/extract-pages-from-pdf/">page extractor</a>, or split a long document with <a href="/split-pdf-into-multiple-files/">split PDF</a> and send it in parts.

Will the recipient notice any difference?

No. The compression is lossless — same pages, same text, same images, just a tighter file.

Is it safe for confidential documents?

The file never leaves your browser: compression runs locally in the tab. Encrypted PDFs are rejected, so unlock a copy first if you have permission.

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