How to Make a PDF Smaller for Email and Online Forms

Why PDFs get so large

A PDF itself is not heavy. What adds weight is what is inside: scanned pages saved as big images, high-resolution photos, and embedded fonts. A scan of ten pages at a high resolution can easily reach tens of megabytes.

Know your limit

Many email services limit attachments to roughly 20 to 25 MB. Government portals, job sites and university forms are often much stricter, sometimes only 1 to 5 MB or even a few hundred KB. Always check the limit before you start, so you know your target.

How to compress a PDF

1. Open the compress PDF tool.
2. Choose your file.
3. Type the size you need, for example 500 KB.
4. Run the compression, which happens in your browser.
5. Open the result and check every page.

Check the result

Make sure the text is easy to read, signatures are clear and small print is still legible. If it is too blurry, aim for a slightly larger target size. If you need to search or copy text from the PDF, check that this still works as well.

Prevent big PDFs in the first place

• When you scan, use around 300 dpi for text documents. 150 dpi is often enough for forms.
• Scan in black and white or greyscale when colour is not needed.
• Resize big photos before putting them in a PDF.
• Split a very long document into parts if it is still too big.

Other options

If a PDF is really just a set of pictures, you can convert its pages to images, resize and compress them, and rebuild the PDF with image to PDF.

Choosing a target size

If a form says “maximum 2 MB”, set the target a little below it, such as 1.8 MB, to leave a safety margin. For email, aim well under the limit of the receiving server, because attachments grow slightly when they are encoded for sending.

Keep your original

Compression cannot be undone. Always keep the original file and send the smaller copy.

Frequently asked questions