Compress PDF

How it works

Choose a PDF and a level: high quality, balanced, or maximum compression. The tool recompresses embedded images (photos, color or grayscale scans), downsizes them to the resolution they need, and shows file size before and after. How much it reduces depends on the PDF: one full of photos reduces a lot; one that is mostly text barely reduces at all.

Only images are modified. Text and vector graphics stay exactly the same, and pages retain their size and appearance. Recompressed images lose some quality, which is why your original is not modified: a new file is created on your device, without uploading anything.

Some images are left untouched because recompressing them would not be safe: images with a color-key mask, CMYK color images, and black-and-white scans. When finished, we show how many were recompressed, how many were not, and why. If the file cannot be reduced, we offer the original unchanged. Password-protected PDFs can be compressed: the site asks for the password and the result is saved without a password.

What is not preserved, and limits

• Only standard grayscale or RGB images are recompressed, including those inside reusable page blocks. Images in CMYK or other special color spaces, 1-bit images (black-and-white scans), images in JBIG2, CCITT or JPEG 2000 formats and images with a color-key mask are left untouched.
• Some PDFs reduce little or not at all: those that are mostly text, those with already well-compressed images, and those sharing resources across pages. In a portion of our test PDFs, no reduction was achieved; when that happens, we provide the original unchanged.
• Recompressed images lose some quality and their color profile.
• PDFs with thousands of pages can take a while: the screen shows the progress and you can cancel at any time.
• If the file is damaged and has to be rebuilt with the fallback engine, bookmarks and document information are lost, similar to merging.
• A digital signature ceases to validate.
• Password-protected PDFs can be compressed: the site asks for the password and it is only used in your browser, never saved or sent. The result is saved without a password.
• Very large files (over roughly 100-150 MB total, or with thousands of pages) may fail, especially on mobile devices, because everything runs in your device's memory.