You attach the PDF, hit send, and it bounces: “attachment exceeds the size limit.” The document is only a few pages — why is it 30 MB? Here’s what’s bloating it and how to get it small enough to send without it looking terrible.
Short answer: Most email limits sit around 25 MB (aim for under 10 MB to be safe). PDFs get huge because of embedded images, so the fix is to compress them. Run the file through the Compress PDF tool — it shrinks the images in your browser, no upload required.
The real attachment limits
| Service | Attachment cap |
|---|---|
| Gmail | 25 MB |
| Outlook / Microsoft 365 | 25 MB (admins can set this higher or lower) |
| Yahoo Mail | 25 MB |
| Many company mail servers | 10 MB or less |
Two catches make these smaller than they look. First, the cap is applied to the encoded message, and encoding adds roughly 35% — so the real ceiling is closer to 18–19 MB of actual file. A PDF that looks safely under 25 MB on your disk can still bounce. Second, the receiver’s limit matters as much as yours. The reliable target is under 10 MB, which sails through almost everywhere.
Why PDFs balloon
The culprit is nearly always images. A PDF’s text and vector shapes are tiny — a hundred pages of pure text is a small file. But the moment you scan documents or export from a design app, the PDF embeds full-resolution photos, frequently at 300 DPI or higher. That’s print quality baked into a file most people will only ever read on a screen, where anything above ~150 DPI is invisible.
So “my 4-page PDF is 28 MB” almost always means “my 4-page PDF contains four full-resolution photographs.”
Getting under the limit
1. Compress it. This is the fix 90% of the time. The Compress PDF tool downsamples the embedded images to a screen-sensible resolution — usually cutting the file by 70–90% with no difference you’d notice on screen. Because it runs in your browser, the document (a contract, a scan of your passport) never leaves your device.
2. Split it. If a single PDF is genuinely huge because it’s long — a 200-page report — sending half now and half later may beat compressing. Use Split PDF to break it into parts that each fit.
3. Fix it at the source. If you’re the one assembling the PDF from images, shrink the images first with the Image Compressor, then combine them. A PDF built from right-sized images never balloons in the first place — see how to reduce image file size.
The one mistake to avoid
Don’t compress the same PDF over and over. Image compression is lossy — each pass throws away a little more detail, and stacking passes is how a readable scan turns into a smear. Compress once, from the highest-quality original you have. If the result is too big and too rough, the file is better split than crushed further.
When you’re combining files anyway
Often the oversized-PDF problem shows up while you’re assembling something — stitching receipts, merging a signed contract back together. Do the shrinking as part of that step: merge your PDFs first, then run one compression pass on the finished document. One clean file, under the limit, sent on the first try.