How ConvertirDocs compresses a PDF
To compress a PDF, ConvertirDocs uses its own engine that works on the photos inside the file. It recompresses JPEG images and 8-bit color or grayscale photos, and leaves everything else alone. Text and vector graphics, such as lines, charts and logos drawn as shapes, are not touched, so the text stays sharp and you can still select, search and copy it.
The engine also removes things you don't see: embedded page thumbnails and XMP metadata. Some image types are kept exactly as they are because recompressing them could damage them: images with transparency, 1-bit black-and-white images, indexed-color images, CMYK images, and JPX or JBIG2 images.
Choosing a compression level
There are three levels. Low limits photos to 2400 pixels on their longest side at 85% quality, which is a good choice when you plan to print. Recommended uses 1700 pixels at 70% quality and suits most documents you read on screen or send by email. Extreme goes down to 1100 pixels at 50% quality, for when size matters more than detail.
If a website or form asks for a file under a specific size, use “Compress to X KB” instead. Type the target and ConvertirDocs lowers the quality step by step until the file fits. If it can't get there, you still get the smallest version it managed, plus a short explanation of why. We also have ready-made pages for common targets: 100 KB, 200 KB, 500 KB and 1 MB.
What kind of PDF shrinks the most
Scanned documents and PDFs full of photos usually shrink well, because most of their weight is images. A scanned contract, a photo report or a brochure exported at high resolution are typical examples.
A PDF made only of text and fonts, like a document exported from a word processor, often shrinks very little. There are no photos to recompress, and the text itself is already compact. If the result isn't smaller than your original, ConvertirDocs gives you the original back with the message “Your PDF is already optimized”, so you never download a bigger file by mistake.
Your file stays on your device
Compression runs entirely in your browser. The PDF never leaves your device, nothing is uploaded, and nothing is stored. That matters when you are shrinking a bank statement, a medical report or a passport scan for a visa application.
It's free, with no account, no email and no usage limit. The only limit is your device's memory. With very large files, over 150 MB on a phone or 500 MB on a computer, you'll see a warning, but you can still try.