How to compress a PDF without losing quality

Why some PDFs are so heavy

The size of a PDF depends on what is inside it. Plain text takes up very little space: a hundred-page text-only report is usually under 1 MB. What weighs a lot are images. High-resolution photos, charts exported as images and, above all, scanned pages, where each page is a photo, can take a document to tens of megabytes.

That is why the same contract can be 200 KB when exported from Word and 15 MB when scanned. Before compressing, it is worth knowing which of the two cases you have, because the possible savings are very different.

When compressing makes a difference

Compression works well on PDFs with images: scans, exported presentations, catalogs and documents with photos. In those cases, lowering the image quality can cut the file by more than half with no noticeable difference on screen.

Text-only PDFs, on the other hand, are already light and compression barely changes their size. If a text document is heavy, the reason is usually an image embedded by mistake, such as a logo at a very high resolution.

How to compress a PDF step by step

With the Compress PDF tool, the process takes less than a minute:

1. Upload the file, up to 60 MB.
2. Keep the default quality level of 75%, which balances size and appearance in most cases.
3. Click compress and wait for processing.
4. Download the result and open the file to check that the text and images are still readable.

How to choose the quality level

There is no single ideal value. A rule of thumb: for documents that will be read on screen or sent by email, 60% to 75% is usually enough. For documents that will be printed or have small print, choose higher values. Below 50%, photos and scans start to look visibly worse.

Always start with the default value. If the file is still above the required limit, try again with a lower value, comparing the result each time.

What to do if the PDF is still large

If compression was not enough, there are other options:

• Split the document into parts with Split PDF and send each part separately.
• If the PDF is a color scan of a text-only document, scan it again in black and white or grayscale, which greatly reduces its weight.
• If you created the PDF from images, shrink the images first with Compress Image and build the PDF again.
• Remove unnecessary pages, such as duplicate covers and blank pages.

Care when compressing important documents

Always keep the original file. Compression creates a new version, and what was discarded from the images cannot be recovered later. For documents that require maximum fidelity, such as technical drawings and files headed for professional printing, compress only if the upload limit really requires it.

If the PDF is a scan and you also need to search the text, run OCR with the PDF to OCR tool. The text layer adds very little weight and makes the document much more useful.

Frequently asked questions