Compress PDF to 100KB

Will a PDF compressed to 100KB still be readable?

On screen, usually yes — but check. At the lowest step images are 72 DPI, which makes a full A4 page about 595 × 842 pixels. Normal printed text survives that; small print, stamps, handwriting and signatures are the first to blur.

After compressing, open “Compare with original”: the two versions appear side by side and zoom together, so you can read the same corner of each. If something important is no longer legible, crop the scan tighter, scan only the part that is required, or check whether the site accepts a larger file.

Compress PDF to 100KB with several pages

One hundred kilobytes shared by several pages leaves very little for each: three scanned pages get roughly 33 KB apiece. Multi-page scans rarely get there with Recommended or Smaller, because those levels stop at 72 DPI and never touch images that are not JPEG.

Try Smallest first; it redraws every page and has the most room to shrink. If it still cannot get under 100 KB, the note under the result says so. The realistic options then are fewer pages, a grayscale scan, or one file per page when the form has separate upload fields.

When not to use Smallest

Smallest replaces each page with a picture of it: text can no longer be selected, copied or searched, and links and fillable fields stop working. That changes nothing for a scan. For a form you fill in on screen, or a document someone needs to search, stay with Recommended or Smaller and accept a slightly larger file if the site allows it.