How to Compress a PDF Without Losing Quality (Practical Guide)

PDFs are great for sharing, but they can become painfully large—especially when the file includes scanned pages, high-resolution photos, or screenshots. The good news: you can often shrink a PDF dramatically without making it look bad. The key is understanding what is taking space and choosing the right compression strategy.

Step 1: Identify what makes the PDF heavy

In most cases, large PDFs are large for one of these reasons:

• Embedded images (photos or scans) are high resolution and/or poorly compressed.
• Scans are stored as full-page images, even if the page is mostly white background.
• Unnecessary color (for documents that could be grayscale).
• Duplicate resources (multiple copies of similar images, fonts, or objects).

If your PDF is mostly text and still huge, it’s usually because it contains images or scanned pages you can’t immediately see at first glance.

Step 2: Compress the PDF using a balanced preset

For most documents, the best starting point is a balanced preset. On our site, go to Compress PDF and choose Medium. That usually keeps text crisp while reducing images enough for email and messaging apps.

If you need the smallest file possible (e.g., an upload limit), choose Low. If the result becomes too blurry, go back and choose High instead.

Step 3: If it’s scanned, consider grayscale

Scanned documents are often stored as color images—even when you only need black & white. Converting to grayscale can reduce size and improve readability for printing. Try Grayscale PDF, then run compression again.

Step 4: Convert pages to images only when needed

Sometimes you need a lightweight image preview instead of the full PDF. If that’s your goal, use PDF to JPG or PDF to PNG. This exports each page to an image and packs everything into a ZIP file. It’s great for sharing a few pages as images, but it’s not always the best way to preserve selectable text.

Step 5: Remove pages you don’t need

It sounds obvious, but it works: removing unnecessary pages can instantly reduce size. Use Remove Pages to delete pages like cover sheets, blank pages, or duplicate scans.

Common mistakes (and how to avoid them)

• Over-compressing too early: Start with Medium. Only go to Low if you truly need it.
• Assuming “PDF = text”: Many PDFs are actually images (scans). Treat them differently.
• Not checking output: Always open the compressed PDF and verify the critical pages.

Next steps

If you’re trying to send a PDF by email, compress first, then verify the result. If you’re sharing on a messaging app, consider converting only the required pages to images. For more tips, read: How to choose the right DPI for PDF to PNG.