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Gmail Attachment Size Limit — and How to Send Bigger Files

By MyPDFKitty Editorial Team · Updated 2026-05-01

Quick answer

Gmail limits attachments to 25 MB, but base64 encoding adds ~33% in transit, so files over ~18 MB on disk can hit the limit. To send larger files: compress first, split the PDF if compression isn't enough, or use Gmail's automatic Google Drive integration (Drive link in the email). Outlook 20 MB, Yahoo 25 MB, iCloud 20 MB.

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The 25 MB number isn't quite the truth

Gmail's documented attachment limit is 25 MB, but that's the encoded size — the size of the file once it's been base64-encoded for email transit. Base64 encoding inflates binary files by roughly 33%. So a 19 MB PDF on your disk becomes ~25 MB in transit and may bounce. Aim for 18 MB or less on disk to be safe.

Limits at other providers

What gets your PDF over the limit

Three ways to send big files via Gmail

  1. Compress the PDF — usually fastest, keeps the email self-contained
  2. Use Gmail's Google Drive integration — it automatically prompts you when an attachment is too big and inserts a Drive link instead
  3. Split the PDF and send in two emails — works for review documents that aren't sequential-dependent

When to use a file-share link instead

If your PDF is over 50 MB even after compression, or if you're sending to recipients on tight enterprise email systems (10 MB caps are common), use a Drive / Dropbox / WeTransfer link rather than try to attach. Compressed direct attachments are faster for the recipient when they fit, but a link beats a bounced email every time.

Step-by-step

  1. Step 1

    Check the file size

    If your PDF is over 18 MB on disk, it'll likely hit Gmail's limit.

  2. Step 2

    Compress

    Run our compress tool — most documents shrink 50–80%.

  3. Step 3

    Or use Google Drive link

    Gmail offers a Drive upload automatically when an attachment is too big.

  4. Step 4

    For very large PDFs, split

    If compression isn't enough, split into two and send in two emails.

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FAQ

What's the maximum email attachment size for Gmail?+

25 MB encoded. Base64 inflates files ~33%, so plan for 18 MB on disk maximum.

How do I send a PDF larger than 25 MB?+

Compress first, or use Gmail's Drive integration which kicks in automatically when the attachment is too big.

Why does Gmail say 'attachment is too big' even though my file is under 25 MB?+

Base64 encoding adds ~33% in transit. A 22 MB file on disk hits ~29 MB encoded — over the limit.

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Gmail limits attachments to 25 MB, but base64 encoding adds ~33% in transit, so files over ~18 MB on disk can hit the limit.

Compress PDF