The classic "send it to yourself first, get the bounce, compress, try again" loop is avoidable. Here are the actual attachment limits and the fastest way to check before you send.
Email attachment limits (the actual numbers)
| Provider | Hard limit | Soft warning | Notes | |---|---|---|---| | Gmail | 25 MB | none | Sends 25 MB total including encoding overhead. A 24 MB file often fails because base64 encoding inflates it. | | Outlook.com / Hotmail | 25 MB | none | Same 25 MB, same encoding caveat. | | Apple Mail (iCloud) | 20 MB | 20 MB | Sends 20 MB. Anything larger silently bounces. | | Yahoo Mail | 25 MB | none | Same 25 MB, same encoding caveat. | | Most business SMTP | 10–25 MB | 10 MB | Exchange and corporate relays often cap at 10 MB. | | Most mobile apps | 5–10 MB | 5 MB | Mail.app, Gmail app, Outlook app all have smaller caps than web. |
The practical limit is 10 MB if you don't know who you're sending to. Above 10 MB, some recipients will bounce. Above 25 MB, everyone will.
The "encoding inflation" gotcha
A 24 MB PDF often fails to send through Gmail even though the limit is 25 MB. The reason: attachments are encoded in base64 for transport, which inflates the file by roughly 33%. So a 24 MB file becomes ~32 MB in transit and exceeds the 25 MB server-side limit.
If you're within 10% of the limit, compress the file first.
How to check before you send
The fastest check is DocShop's free PDF size check. Drop the file, get an instant verdict:
- Email-friendly (under 10 MB) — send it, no problem.
- Large but attachable (10–25 MB) — it'll probably get through, but some providers will warn or bounce. Compress to be safe.
- Too large (over 25 MB) — definitely bounce. Compress or split.
The check runs entirely in your browser. The file is never uploaded to a server. You also get a page count, encryption state, and an estimate of how much compressing would save.
What to do when your PDF is too big
Option 1: Compress
Use Compress PDF with the ebook preset. It downsamples images to 150 DPI (screen-readable) and re-encodes the whole document. Typical savings:
- 600 DPI scanned contract: 70–90% smaller
- 300 DPI brochure: 50–70% smaller
- Text-only report: 10–30% smaller
For most use cases, ebook quality is the sweet spot. Use screen for really aggressive compression (will look slightly soft on print). Use printer or prepress only when the recipient will actually print at high quality.
Option 2: Split
If the PDF is genuinely long (a 200-page contract, a 500-page manual), splitting is often better than compressing. Use Split PDF to extract just the chapter or pages you need.
Rule of thumb: if the file is over 25 MB AND the page count is over 100, split it. If the page count is under 50, compress.
Option 3: Use a link, not an attachment
Modern tools let you share a link instead of attaching the file. DocShop's share-link feature (Pro tier) creates a one-time download URL that expires in 1 hour. The recipient clicks and downloads; you never hit an attachment limit.
Privacy note
Most free online PDF compressors require an upload. DocShop's size check runs entirely in the browser — the file never leaves your device. The Compress tool does upload (you can't compress a file without processing it), but we delete the upload and the result within 1 hour, never read the content, and run the conversion in an isolated container with no human access.
See How we handle your files for the full timeline.