How to use it
- Choose the PDF. Its page count appears under the name.
- Pick a Resolution. 72 dpi gives the smallest file and is fine for reading on screen; 150 dpi suits most printing.
- Set the JPEG quality. A lower value makes the file smaller and the pictures softer.
- Click Make the smaller PDF, compare the two sizes shown, then Download.
What the smaller file keeps and loses
Each page is drawn in your browser by pdf.js at the resolution you chose, saved as a JPEG and placed on a new page of the same size. The page layout and the images look as they did on screen, but the page is now one picture.
That is why the text can no longer be selected, copied or searched, and why links, bookmarks and form fields are gone. Keep the original file if you still need them.
When compressing helps
Scans and photographs of pages are already pictures, so this tool shrinks them a great deal with little loss. Large files with many photos shrink too. A text document with little in it often gets bigger, because a JPEG of a text page is not smaller than the text itself.
The tool checks this: when the new file would be larger than the original, nothing is made and the message gives both sizes.
- Lower resolution and lower quality give the smallest files.
- Very large pages are drawn at a lower resolution than asked, to stay within the browser's memory; the page keeps its size.
Example: a scanned 20-page contract
A scanned contract of 20 pages was made with a high scanner resolution, so its file is large. Choose 150 dpi and a JPEG quality of 70 %, then make the smaller PDF.
The two sizes shown after compressing are the exact figures for your file. The scan still reads well on screen, but the text is no longer searchable, so keep the original if you need search.
Frequently asked questions
Are my PDF files uploaded anywhere?
No. Your browser draws each page and makes the smaller file on your own device. Nothing is sent to our server.
Can I still search the text after compressing?
No. Each page is a picture, so the words cannot be selected or searched. Use the original file for search, or run a text recognition tool on the result.
Why did the tool refuse to make a file?
The new file would have been larger than the original, which happens with small text-only documents. Nothing is offered in that case. Your original is not changed.
What resolution should I choose?
72 dpi is enough for reading on a screen. 110 to 150 dpi suits most documents you print, and 200 dpi keeps small print sharp at a larger size.
Why is one page less sharp than the others?
A very large page is drawn at a lower resolution so that your browser can handle it. Its size on paper is unchanged.
Does it work on a phone?
Yes, in any up-to-date browser. A long or large file takes longer on a phone, so a smaller file or a lower resolution is quicker.
Sources
- pdf.js, the open-source library that draws each page in your browser
- pdf-lib, the open-source library that builds the smaller PDF
Figures and text last checked on Tuesday, November 10, 2026.