How to Compress a PDF Without Losing Quality

You finish a report, scan a signed form or export a presentation — and the PDF is 30 MB. Your email bounces it, the job portal says "maximum 2 MB", and the file takes ages to open on your phone. The good news is that most large PDFs can be made dramatically smaller in seconds. The trick is knowing why the file is big, so you can choose the right kind of compression and keep the quality you care about.

Why PDFs get so large

A PDF is a container. The text itself is tiny — a 50-page report of plain text might be under 200 KB. The size comes from what else is packed inside:

• Images and scans. A single page scanned in colour at 600 DPI can be 5-10 MB on its own. Phone photos are often 3-4 MB each.
• Embedded fonts. PDFs embed fonts so the document looks the same everywhere. Some fonts, especially for Asian scripts, are several megabytes.
• Unoptimized structure. Some programs save PDFs with duplicated resources, uncompressed data streams or leftover editing history.
• Vector graphics. Detailed charts and maps exported from design tools can contain hundreds of thousands of drawing instructions.

Once you know which of these applies to your file, choosing a compression method is easy.

Two kinds of PDF compression

Lossless compression

Lossless compression reorganizes the file internally: it removes duplicate objects, packs small objects together and recompresses data streams with stronger settings. Nothing you can see changes — text stays selectable and searchable, links still work and images keep their original resolution.

Lossless compression is the right choice for contracts, invoices, academic papers and any document that someone may need to search or copy text from. The trade-off is that savings are modest, typically 5-30%, because text-based PDFs are already efficient.

Image (lossy) compression

Image compression re-creates each page as an optimized JPEG image at a sensible resolution. For scanned documents — which are already images — this is exactly what you want: a page scanned at 600 DPI can be reduced to 110-150 DPI and still look crisp on any screen. Reductions of 50-90% are common.

The trade-off is that pages become pictures, so any selectable text in the original is no longer selectable. For scans this makes no difference, because the text was never selectable to begin with.

Step-by-step: compress a PDF with MyPDFConverters

1. Open the Compress PDF tool.
2. Drag your PDF onto the upload area, or click to choose it. The file is read by your browser — it is not uploaded anywhere.
3. Choose a compression level:
   • Recommended — best for scans and image-heavy files.
   • Extreme — the smallest possible file, for strict upload limits.
   • Lossless — keeps text selectable and quality identical.
4. Click Run Compress PDF. The tool compares every result with your original and gives you the smallest one, together with how much space you saved.
5. Open the downloaded file and check that it is readable before you send it.

How small does it need to be?

Different services have different limits. These are typical values in 2026 — always check the exact limit shown on the form you are using:

If you need to hit a very small target such as 500 KB, start with Recommended, then try Extreme if needed. For multi-page scans, removing unnecessary pages with Remove Pages helps as much as compression does.

Tips to keep quality high

• Scan at the right resolution. 200-300 DPI is plenty for documents. 600 DPI only makes files huge.
• Scan in greyscale when colour is not needed — colour scans are roughly three times larger.
• Compress once. Compressing an already compressed file repeatedly lowers quality with little extra saving.
• Keep the original. Store the full-quality file and send the compressed copy.
• Check small text. After compressing, zoom in on footnotes and signatures to make sure they are still readable.

Common mistakes to avoid

Compressing a password-protected PDF. Encrypted PDFs cannot be restructured. Remove the password with Unlock PDF first, compress, and protect it again with Protect PDF if needed.

Using image compression on a document people need to search. If the recipient needs to search or copy text — for example a contract they will quote from — use Lossless mode instead.

Uploading sensitive documents to unknown websites. Many free tools upload your file to their servers. Prefer tools that process files locally in your browser, like ours, especially for ID cards, bank statements and medical records.

Conclusion

Most oversized PDFs are big because of images. Choose image compression for scans and photos, lossless compression for text documents, and always check the result. With the right method, you can usually make a PDF small enough for any form or inbox without anyone noticing a difference in quality.