Gmail Attachment Limit: How to Make PDFs Fit

Step 1: Start with the Gmail 25 MB preset

Select the Gmail preset to target 25 MB. PDFThin will optimize without visible changes when possible.

If the file still fails to send, drop to a smaller custom size to account for overhead.

Step 2: Compress scans and heavy images

Scanned PDFs are image-heavy, so they often require stronger optimization. Smart quality helps you keep legibility while shrinking the file.

If you control the scan, lower the DPI or use grayscale to reduce file size before upload.

Step 3: Split if a single file cannot fit

When one PDF cannot fit even after compression, use Split by size to get multiple parts under the Gmail limit. Attach all parts in order and mention in your email that the PDF is split for size.

Step 4: Verify the attachment

After compression or splitting, check the new file size before attaching. This avoids last-minute send errors.

If you still see warnings, reduce the target size by a few MB and retry.

What happens if I exceed Gmail limits?

Gmail replaces the attachment with a Google Drive link. If you need true attachments, compress or split first.

Does Gmail compress PDFs?

No. Gmail does not shrink your PDF. You must compress it before attaching.

Is 25 MB always safe?

Not always. Encoding overhead can push the email over the limit. Try 20 MB if you see errors.

Aim for a cushion

Targeting slightly below 25 MB gives you a safety margin for email encoding and other attachments.

A 20 MB target usually sends reliably across Gmail and other providers.

Keep file names clear

Short file names reduce clutter and make it easier to identify attachments for recipients.

Use a name like Project-Report-25MB.pdf for quick context.

All PDF tools

Browse every PDFThin tool in one place.

Email-ready compression

Shrink PDFs to Gmail/Outlook limits with quality control.

Split by size

Split large PDFs into size-safe parts.

Organize PDF

Merge, rotate, delete, reorder, and split pages.

All PDF guides

Browse every step-by-step PDF guide.

Compress PDF for email (complete)

Step-by-step workflow for Gmail 25MB and Outlook 20MB limits.

Reduce scanned PDF size

Keep text readable while shrinking scanned documents.

Split PDF by size

Create parts that stay under a target MB limit.

Rotate PDF pages online

Fix page orientation for sideways scans or photos.