Send a large PDF without shrinking it

Why is my PDF too large to email?

Most mail services cap a message at 20 to 35 MB, attachments included (Gmail and Outlook.com 25 MB, Microsoft 365 35 MB by default, iCloud Mail 20 MB, as of October 2026). Attachments also grow by about a third once encoded for email, so a 20 MB PDF can already bounce. And PDFs get big quickly:

An uncompressed A4 page scanned at 300 dpi in colour is about 26 MB of raw image data (2,480 × 3,508 pixels × 3 bytes); scanners compress it, but a long scanned file still adds up fast. More on email caps in email attachment size limits.

How to send a large PDF with Transfr

1. 1

   Step 1

   Open Transfr

   Go to Transfr. No sign-up needed.

2. 2

   Step 2

   Add your PDF

   Drop the file, or several PDFs and their source files, up to 100 GB per transfer.

3. 3

   Step 3

   Turn on comments for a review

   If you want feedback, enable comments. Readers can attach a note to a specific page.

4. 4

   Step 4

   Send by email or link

   Type up to 10 addresses, or copy the link into your own email. Add a password for anything confidential.

Should you compress a PDF to send it?

Compressing works by lowering the resolution and quality of the images inside the PDF. That is fine for a document someone will only read on screen. It is a bad idea for anything that will be printed, zoomed into or archived:

• Print files need their full-resolution images; a print shop will reject a compressed PDF or print it soft.
• Plans and technical drawings lose fine lines and small text when rasterised or downsampled.
• Signed or certified documents can lose their signature validity if the file is rewritten.
• Archives should keep the original; you cannot add quality back later.

Sending a link skips the trade-off entirely: the recipient gets the exact file you exported. If you do need a light version for quick reading, send both in the same transfer.

Read and review the PDF in the browser

On the download page, PDFs open directly in the browser, so your recipient can read a 300-page report or flip through a catalogue without downloading it first. With comments turned on, they can leave a note on a specific page: “typo in the second paragraph”, “swap these two photos”. You receive an email when a comment arrives.

This makes Transfr a lightweight proofing tool for designers sending layouts to clients, students sending a thesis to a supervisor, or teams reviewing a report. Word, Excel and PowerPoint files also preview, which helps when the PDF comes with its source documents.

One big PDF or several smaller ones?

With email, people split documents to squeeze under the limit. With a link, size is no longer the reason to split, so decide based on how the recipient will use them:

• One PDF when the document is read from start to finish, or printed as a single job.
• Several PDFs in a folder when people will jump to one chapter, one plan sheet or one invoice. Name them so they sort in order (01-Cover, 02-Plans…).
• A folder with the PDF and its sources when the recipient may need to edit. Folders keep their structure in the transfer, see sending a folder without zipping.

Scanned a document on your phone? The same works from a mobile browser: open Transfr, pick the PDF from the Files app and send the link. See sending large files from an iPhone.

Sending confidential PDFs

Contracts, payslips, medical reports and ID scans should not sit in mailboxes indefinitely. A transfer gives you control an attachment cannot:

Law firms and accountants will find more in secure file transfer for law firms, and everyone in secure file transfer. To collect signed documents back, create a file request.

Large PDFs for printers and publishers

Print shops receive PDFs of hundreds of megabytes every day. Ask yours whether they prefer one PDF per section or a single file, and send everything in one transfer so nothing gets lost between emails. If you run a print shop, a permanent file request link on your website lets customers send print files of up to 100 GB without an account.