In this guide
Why emails reject large PDFs
Every email provider applies an attachment limit. Gmail allows 25 MB, Outlook.com allows 20 MB, and Yahoo caps attachments at 25 MB. But those are hard limits — before you hit them, the file becomes painfully slow to upload and the recipient waits minutes for the download.
The main reason PDFs become huge is embedded images. Scanned pages, screenshots and photos stored inside a PDF are often saved at a much higher quality (and resolution) than the document actually needs. A 30-page scanned PDF can easily reach 40–80 MB, which no email service will accept.
Compression fixes this by re-encoding the images inside the PDF so the pages stay readable while the file gets much smaller. Text-heavy PDFs shrink the least — but a scanned or image-heavy PDF can often be reduced by 60–80 percent.
What size should a PDF be for email?
There is no single correct answer, but a practical target is under 10 MB for most recipients. It uploads quickly, downloads quickly and stays comfortably inside every provider's limit.
For text-only documents (contracts, invoices, letters), aim for 1–5 MB. For scanned documents and reports, 5–15 MB is usually acceptable. If the file is still too large after strong compression, split it into smaller files or send it via a file-transfer link instead.
How to compress a PDF in 3 steps
- Open the compressor. Go to the PDF Compressor page. Everything runs in your browser, so nothing is uploaded.
- Drop in your file. Drag the PDF into the box or click to browse. Files up to 100 MB are handled.
- Pick a level and download. Choose Fast for a quick shrink, Balanced for good quality and size, or Strong / High Strong for the smallest files. Click Compress & Download and save the result.
The tool shows the original and new sizes side by side, so you can see how much space you saved before downloading.
Tip: keep the compressed copy as your “send” version and the original as your archive. Compression is lossy for images, so always keep the master file for editing and print.
Keeping quality while shrinking size
Compression works by lowering the quality of embedded images. The trick is to lower it just enough to shrink the file without making text or photos look bad.
- Start with Balanced. It re-encodes images at a moderate quality level that keeps pages clean while cutting size dramatically.
- Only go Strong for scans and archives. If the PDF is mostly text, strong compression barely reduces quality anyway.
- Check the result. Open the compressed file and scan a couple of pages. If any image looks blurry, retry with a lighter level.
- Text stays perfect. The text layer of a PDF is not compressed the way images are, so searchable text remains sharp.
Before you send: a quick checklist
- Is the file under your email provider's limit? (Aim for 10 MB or less.)
- Did you open the compressed file and check the pages?
- Is the document still readable if printed?
- If it is a contract or signed document, is the signature still clear?
If you are combining several documents, compress them first and then merge the PDFs into one attachment.
Frequently asked questions
Why won't my email accept the PDF?⌄
Your file is almost certainly over the provider's attachment limit. Compress it to under 10 MB, or use a file-sharing link for very large documents.
Does compressing a PDF reduce its quality?⌄
It reduces the quality of embedded images slightly. The text remains crisp. Using a Balanced or Fast level keeps the difference invisible for most documents.
Can I compress a PDF without losing quality for text?⌄
Yes. Text is re-rendered rather than re-encoded as an image, so a text-heavy PDF stays sharp even with strong compression.
What is the largest file the compressor can handle?⌄
The PDF Compressor handles files up to 100 MB. If your PDF is bigger, try splitting it first with the Organise Pages tool.
Is my PDF uploaded to a server?⌄
No. The entire process runs locally in your browser. Your document never leaves your device.