How-to guide · LocalPDF
How to compress a PDF for email (without uploading)
Email still rejects or throttles huge attachments. A 15MB scan can bounce, clog shared inboxes, or get stripped by security gateways. This guide shows how to compress a PDF for email privately in your browser with LocalPDF — pick the right strength, hit common size caps, and keep sensitive files off third-party servers.
By: LocalPDF Team · Updated 2026-07-31
Step-by-step
- Open Compress PDF on https://www.openlocalpdf.com/compress/.
- Drop the attachment candidate into the browser drop zone (local read only — no upload for processing).
- Choose Balanced for most email; Strong if you already hit a size bounce.
- Run Compress PDF and download the smaller file.
- Check the on-page size summary and open the PDF once (zoom signatures if any).
- Attach to Gmail/Outlook/work mail. If it still bounces, retry Strong or split pages.
Advertisement
Common email size limits (rules of thumb)
Providers differ, and corporate gateways are often stricter than consumer Gmail. When in doubt, aim smaller than the published maximum so the message survives forwarding.
- Many consumer inboxes: practical comfort zone under ~10–25MB total message size
- Corporate mail: often 10MB or less for attachments
- If recipients are on mobile data: under 5MB is polite
- Forms that ask you to “email the PDF” may still enforce 2MB — see the under-2MB guide
Why email PDFs get huge
Phone scans, camera exports, and “print to PDF” from image-heavy slides dominate oversized attachments. Text-only exports are usually already email-friendly.
Compressing rasterizes and re-encodes pages as JPEG at your chosen quality. That is ideal for scans; it is optional for small text PDFs.
Which compression level for mail?
Balanced is the default for most email. Strong when a gateway still rejects the file. Light when the recipient must read fine print or signatures at zoom.
- Invoices / receipts scans → Balanced, then Strong if needed
- Signed contracts → start Light or Balanced; verify signature clarity
- Photo-heavy decks → Strong + consider fewer pages
- Already-small text PDF → skip compress; attach as-is
Etiquette and deliverability tips
Name the file clearly (invoice-2026-07.pdf). Mention in the email body that you compressed a scan for size. Keep the full-quality original offline until the thread is done.
If the file must stay perfect and still will not fit, use a trusted company file link — but for one-off personal docs, private browser compress is usually enough and safer than random online converters.
Still too large after compress?
Split the PDF and send part 1 / part 2, or only the pages the recipient needs. Re-scan at 150–200 DPI if you control the source. Remove blank pages before a second compress pass.
FAQ
What size should I target for email? +
Under 5–10MB is a safe courtesy target for most personal mail. Follow your IT policy if you have one; some firms cap near 10MB or less.
Is compressing for email free on LocalPDF? +
Yes. No account. Processing stays in your browser. Ads may fund the free tier after AdSense approval.
Will the recipient see lower quality? +
Scans may look slightly softer on Strong. Always preview before sending legal or medical documents.
Gmail said my file was too large — now what? +
Compress with Strong, split into multiple messages, or remove unnecessary pages. Drive-style links are an alternative when policy allows.
Does this upload my attachment to LocalPDF? +
No. Compression is client-side. See Privacy for how ads (if enabled later) differ from file processing.
How is this different from the under-2MB guide? +
Under-2MB targets hard form portals. This guide focuses on email attachment norms, provider limits, and mail etiquette — often a softer size target.