How to compress a PDF to under 1 MB

What makes a PDF large?

Almost always, images. A scanned page is a photo of the page, often at high resolution and in full colour. Documents full of photos are large for the same reason. A PDF made directly from a word processor is mostly text and is usually small already.

Compress a PDF step by step

1. Open Compress PDF.
2. Add your PDF.
3. Choose Strong for the smallest file, or Balanced if you want a little more detail.
4. Press Compress PDF and check the before and after size shown on screen.
5. Download the smaller file.

Which level to choose

• Strong: the smallest file. Fine for reading on screen and for most upload forms.
• Balanced: a good middle ground for documents with small print.
• Light: keeps the most detail, for documents you might print.

One thing to know first

The compressor works by redrawing each page as an image at a lower resolution. That is what makes scanned PDFs so much smaller, but it also means the text can no longer be selected or searched. Keep your original copy if you need that.

A PDF that is mostly text may not get smaller at all. When that happens the tool gives you your original file back instead of a bigger one.

Still too big?

• Remove pages you do not need with Split PDF, then compress again.
• If the form accepts several files, split the document into parts.
• Next time you scan, use 150 dpi and greyscale for text documents. The file starts out far smaller.

Why 1 MB is not always 1 MB

Some systems count a megabyte as 1,000 KB and others as 1,024 KB. A file that looks like 1.02 MB in one place can be rejected as too big in another. Aim for about 900 KB so you are safely under the limit whichever way the form counts.

What size to expect

Sizes vary a lot, so treat these as rough guides. A full-colour scanned page saved at high quality can be one to several MB on its own. The same page scanned in greyscale at a lower resolution is often a few hundred KB. A ten-page scan therefore may start at 10 to 30 MB and, with Strong compression, often ends up well under 2 MB. Reaching 1 MB depends on how detailed the pages are.

A plan that works for a stubborn file

1. Compress with Strong and read the before and after sizes.
2. If it is still too big, remove pages you do not need with Split PDF, for example blank pages or a cover sheet, then compress again.
3. If the form accepts several files, split the document into two or three parts and compress each one.
4. As a last step, re-scan at a lower resolution. 150 dpi in greyscale is enough for a text document.

Check the result before you submit it

• Open the compressed file and zoom in on small print, stamps and signatures.
• Make sure numbers and dates are still clear, because blurred digits cause rejected forms.
• If something is too soft, try Balanced instead of Strong and compare the sizes.

When not to compress

Because compression turns pages into images, the text can no longer be selected or searched. Keep the original for your records, and do not compress a document that must stay searchable, such as one that someone else will copy text from. For sharing a file that is already small, there is nothing to gain.

Frequently asked questions