How to reduce the size of a PDF
Updated October 7, 2026
A PDF with just a few pages can take up tens of megabytes and be too big for an email. The size almost always comes from photos and scans, not from the text. Compress PDF recompresses the JPEG images (the usual format for photos and color scans) on your device, shows you the size before and after, and leaves the text and drawings exactly as they were.
What makes a PDF large
Text, fonts and vector drawings take up very little space. The size comes from images: photos, scans and pages saved as images. A 20-page PDF scanned in color at high resolution can easily go over 20 MB; with the same content as text only, it would be under 1 MB.
That’s why compressing a text-only PDF barely changes anything, while compressing one with lots of photos can shrink it to a fraction of its size.
Reducing the size, step by step
- Open Compress PDF and drag the PDF into the workspace, or use the button to choose it.
- Choose the “Compression level”. “Recommended” works for almost everything.
- Click “Compress PDF”. You’ll see the size before and after, and you can download the result.
- If it’s still too large, click “Make changes”, choose the “Strong” level and compress again: compression always starts from the original PDF.
Which level to choose
- “Light”: images stay almost the same as the original (only those above 300 dpi are downscaled). The file shrinks less.
- “Recommended”: a good balance for email or sharing (200 dpi and slightly lower quality).
- “Strong”: the smallest file (150 dpi). It shows in photos viewed up close.
Image resolution is measured in dpi (dots per inch): the higher it is, the sharper the image and the bigger the file. For reading on screen, 150 to 200 dpi is usually enough; for high-quality printing, 300 dpi.
When the PDF barely shrinks
If the PDF is already well compressed, or is just text, it shrinks little or not at all. When it can’t be made smaller, MovaDoc tells you and gives you the original, unchanged. There are other ways to make it fit:
- Split it into smaller parts with Split PDF: the “By size” mode creates PDFs that stay under the limit you choose (a page that’s over the limit on its own goes into a PDF by itself).
- Delete the pages you don’t need with Organize PDF.
- If you still have the paper version, scan it again at a lower resolution: 200 dpi is usually enough for reading.
What to check at the end
- Is the final size what you needed? MovaDoc shows the size before and after.
- Zoom in on a photo, a signature and a stamp: are they still legible?
- Can you still select and search the text? You should be able to: the text isn’t changed.
- Did you keep the original? The result is always a new file.