Compress a PDF for email
“Attachment too large”, a send that silently fails, a recipient whose mailbox refuses your document: mail servers cap message size, most often between 20 and 25 MB once attachment encoding is counted — and that encoding inflates the file by about a third. The “target size” field is pre-filled at ~19 MB: a margin under the strictest common webmail limit, which lets the document through even on a constrained Exchange server — and stays well under Gmail’s 25 MB. The tool recompresses in steps — the DPI and JPEG quality of rasterized pages decreasing rung by rung — until the file passes under the threshold; at this comfortable budget the first rungs are almost always enough and quality stays nearly intact. If a very long document remained above the quality floor, the best result achieved would be shown honestly: splitting the PDF across two sends, or sending only the relevant pages, then becomes the right strategy. Everything runs in your browser: neither the document nor the threshold leaves your device.
FAQ
What is the real email attachment limit?
It depends on both ends: your provider and the recipient’s. Gmail tolerates ~25 MB per message, many Exchange servers cap at ~20 MB — and MIME encoding adds ~30% to the file’s weight. The pre-filled ~19 MB stays under the most restrictive scenario.
Why does Gmail reject my 24 MB PDF (limit 25 MB)?
Base64 attachment encoding inflates the weight by about a third: a 24 MB file becomes ~32 MB encoded — beyond the limit. Aim for ~19 MB to pass with margin.
How do I get a PDF of the right size?
The “target size” field is pre-filled at ~19 MB: the tool recompresses in steps until the threshold, then shows the size actually reached. If your server imposes another limit, type it in KB.
Does quality stay good at ~19 MB?
Nearly intact in most cases: this generous budget only requires the first compression rungs, imperceptible on screen. Fidelity of rasterized pages is measured (SSIM) and shown before download.
My 80-page document still will not fit — what now?
Split it with “Split PDF” then compress each part separately, or send only the requested chapter after “Extract pages”. For a no-limit share, an upload link is the classic alternative — but local compression keeps your document off any third-party server.
Is my document sent to a server?
No — analysis, rasterization and PDF rewriting all run locally in your browser: the only network your file meets is your own email send. Verifiable in the Network tab of your developer tools.
What if the best effort stays above?
The loop stops at the quality floor and the size actually reached is displayed — never a false promise. Reducing the page count is then the most effective lever.
What if my file is already under ~19 MB?
Nothing happens to it: a document already under the threshold is returned as-is — the recompression loop only engages when the file actually exceeds the target.
Does my PDF text stay selectable after compression?
Mostly yes: the strategy keeps text-bearing pages as vectors and only rasterizes image-dominated pages. Fidelity on rasterized pages is measured (SSIM) and displayed before you download.
Is a sharing link a better option for a huge file?
An upload-link service works for very large documents — but it puts the file on a third-party server. Local compression keeps the document off the web entirely: for confidential files it is the safer first try.
How to proceed
- Drop your PDF — the “target size” field is pre-filled at ~19 MB (under strict mail-server limits)
- Adjust the threshold if your server enforces another limit
- Run the compression: the first rungs are almost always enough
- Check the size reached and the fidelity (SSIM) before attaching the file
- If the best effort stays above, split the document then compress each part