What PDF compression changes

By Remetric Labs · Last reviewed October 25, 2026

What actually makes PDFs big

Scanned pages and embedded photos are what make a PDF large. The same words stored as text take much less space. Compress PDF does not leave that text in place and re-encode only the pictures. It draws every page as a picture, saves that picture as a JPEG, and builds a new PDF from those pictures. The work stays in your browser.

What the compressor does

Choose a quality level, or type a target size. Each page is drawn at its original page size, encoded as a JPEG, and placed on a new page. A target size tries sharper JPEGs first. If those are still too big, the pages are drawn smaller and tried again. The result says when the file is still above the target, and it says when the new file is not smaller than the original.

What you lose

Because every page becomes a picture, text is no longer selectable or searchable. The rebuild also removes links, form fields, and digital signatures, along with fonts and the original page structure. The quality slider trades sharpness for size. Zoom in and check small type and thin lines before you send the result.

When not to use it

Do not use it when the file must keep selectable text, working links, form fields, or a valid digital signature. Keep the signed original. A text-only PDF is often already small, and this JPEG rebuild can fail to shrink it. Compressing the result again adds more JPEG artifacts. For a print master or a certified exhibit, ask the source for a fresh export. To assemble files first, use combining PDFs, then compress the merged file only if a picture of each page is acceptable.