How to make a PDF lighter
- Choose the document. Drag it into the area above or click to pick it.
- Read what the weight is made of. Images, fonts, page content — measured from your file, not guessed.
- Choose how hard to compress, then press Optimize PDF.
- Check the result: it tells you the old size, the new one, and the difference.
It is called optimize, not compress, on purpose
Only the images are recompressed. The text is never touched.
Most of the weight of a scanned document is images, and that is where there is room to work. Text, on the other hand, is small and precious: re-encoding it would risk the one thing a document exists to carry. So the promise is narrower than «compress», and it is kept.
Two rules that protect you from the tool
If a recompressed image is not smaller, the original is kept. If the whole file is not smaller, you get your document back unchanged, and the tool says so.
A tool that always claims success is a tool you cannot trust. Some documents are already efficient, and on those the honest answer is that there was nothing to gain. Certain images are skipped on purpose and counted: bilevel scans, JPEG2000, images with transparency, and CMYK, where recompressing would lose something the format cannot carry.
Frequently asked questions
Is the document uploaded to a server?
No. Both the measurement and the recompression happen in your browser, on your own device.
Will the text still be selectable afterwards?
Yes. The text is not touched at all: only the image streams inside the document are replaced.
Why did my file not get smaller?
Because there was nothing worth recompressing — a document made mostly of text, or one whose images are already efficient. In that case you get the original back, and the tool tells you rather than pretending.
Is the measurement of the weight exact?
Yes. It is read from the structure of your document without decoding anything, so it is both exact and immediate.