How to Compress a PDF for Email (Under 10 or 25 MB)
To compress a PDF for email, open Compress PDF, choose your file, pick Recommended, and download the smaller copy. The page tells you the new size straight away, so you know before you attach it whether it will fit under your email limit.
Everything happens in your browser. Your PDF is never uploaded, which matters when the file is a payslip, a medical letter or a signed contract.
Steps
- Open Compress PDF and choose your PDF. On a phone, you can pick it from your files or downloads.
- Pick a compression level. Light keeps the best quality, Recommended is a good balance for most email attachments, and Strong makes the smallest file.
- Start the compression and wait a few seconds.
- Read the result line. It shows the old size, the new size and how much smaller the file got.
- Download the compressed PDF and attach it to your email.
How big can an email attachment be?
It depends on who you are sending from and who you are sending to. Gmail lets you attach up to 25 MB. Many work and school email systems set a lower limit, often 10 MB or 20 MB, and the smaller limit of the two sides is the one that counts.
If you don't know the limit, aim for under 10 MB. That gets through almost everywhere. Also keep in mind that email adds encoding to attachments, so a file that sits right on the limit can still bounce. Leave a little room.
Why some PDFs shrink a lot and others barely change
PDFs are big because of the pictures inside them. Scans, photos, brochures and slide decks are full of images, and those are what this tool works on. It re-saves each large image as a JPEG and scales down any image that is bigger than the level you picked needs. On Strong, images are reduced to at most 1,300 pixels on their longest side.
Text, fonts and drawn shapes are left exactly as they were. That's why the text stays sharp and searchable, even on Strong.
A PDF that is mostly text, like a report exported from Word, is usually small already. If compression can't make a file meaningfully smaller, the tool keeps your original quality and tells you so, instead of handing you a worse file.
What to do if it's still too big
- Try Strong. Start again from the original file and choose Strong instead of Recommended.
- Split it. Use Split PDF to break the document into single pages, then join them back into two or three smaller files with Merge PDF and send one per email.
- Send fewer pages. If only part of the document is needed, remove the rest with Organize Pages first.
- Compress several files at once. If you have a batch of PDFs, select them all. Each one is compressed with the same setting, and you can download them all in one ZIP file.
Questions
Will compressing a PDF lower the quality?
Only the images can change. Light keeps them close to the original. Strong makes photos softer, which is usually fine for reading on screen but not for printing photos. Text is never blurred.
Can I compress a PDF on my iPhone or Android phone?
Yes. The tool runs in Safari, Chrome and other modern browsers. Large scans take a little longer on a phone than on a laptop.
Is my PDF uploaded to compress it?
No. The compression runs on your own device, so the file never reaches our servers. You can even install the site as an app and use it without a connection.
Is it free?
Yes. There is no watermark and no signup needed. Guests get one free use per tool each day, and a free account gets three.