Shrink a scanned or photo-heavy PDF by redrawing its pages at a lower resolution, and see the size before and after.
Your files never leave your device. Everything happens in this browser tab.
The compressed PDF is made of page pictures. Its text can no longer be selected, searched or copied, and links and fillable fields stop working. Keep your original.
Scanned documents and PDFs made from phone photos are often far bigger than they need to be, because every page is a large, detailed picture. When a portal caps uploads at 2 MB or an email bounces at 25 MB, that is a problem. This tool makes such files smaller by drawing every page again as a JPEG picture at a modest resolution and putting those pictures into a new PDF.
That method has a real cost, and you should know it before you use it. The new file contains pictures of pages, not the original text, so you can no longer select, search or copy its words, screen readers cannot read it aloud, and links and fillable form fields no longer work. What you see on each page is kept, including filled-in form values. For forms that will be read by a person, that is usually fine. For a contract you may need to search later, keep the original as well.
Resolution is measured in dots per inch (DPI) of the printed page. Low compression draws pages at 150 DPI with JPEG quality 80, which keeps small print crisp. Medium uses 120 DPI and quality 65. High uses 96 DPI and quality 50, which is fine on a screen but can look rough when printed. Each page keeps its original size in the new PDF, so it prints at the same size as before. Very large pages, such as engineering drawings or posters, are drawn at a lower resolution so that phones do not run out of memory.
An A4 page is 8.27 x 11.69 inches. At 150 DPI it becomes a picture of 1240 x 1754 pixels, at 120 DPI 992 x 1403 pixels, and at 96 DPI 794 x 1123 pixels, so High compression has about 41 percent as many pixels as Low. A phone scanner app often saves pages at 300 DPI or more, that is about 2480 x 3508 pixels per A4 page, which is why its files shrink a lot here. A PDF exported from Word or a bank's website is different: its pages are text and lines, which are already tiny, and turning them into pictures usually makes the file bigger.
The tool always measures the new file against your original. If it did not get smaller, it says so and does not offer the download, because a bigger file without searchable text is worse in every way. If it got only slightly smaller, under 10 percent, it tells you that keeping the original is probably the better choice. Password protected PDFs cannot be opened here; save an unlocked copy first if you are allowed to.
Pages are drawn by the open source pdf.js library and the new file is built by pdf-lib, both running inside this browser tab. Your PDF is never uploaded to Ur Next Door or to any other server.
