Compress PDF to 100KB

How the 100KB target is reached

The tool works from the best quality down and stops at the first result that fits:

1. Lossless clean-up of the file structure.
2. Re-saving the photos inside the PDF at lower quality and resolution, keeping text, links and fonts. For PDFs with selectable text this goes as far as photos 560 px wide.
3. Rendering every page as a JPEG, starting at 150 DPI and stepping down through 120, 100, 85 and 72 DPI to 40 DPI, trying several JPEG qualities at each step.

100 KB means 100,000 bytes, so the file also passes forms that count 1 KB as 1,024 bytes. The result shows the exact byte count.

Scanned documents and photos

A scan has no selectable text, so step 2 only goes as far as moderate image reduction; after that, rendering pages at a known resolution gives more readable results for the same size. In tests, a one-page colour scan of 850 KB came out at 66.8 KB with its image re-saved, and a three-page scan at 88.4 KB at 72 DPI.

Greyscale removes colour information, which helps documents that are black text on white paper. If a scan was made at a very high resolution or in colour, rescanning at 150–200 DPI in greyscale gives a better starting point than any compression afterwards.

When 100KB isn't possible

Every page needs a minimum number of bytes to stay legible. In the tests above, an A4 scan rendered at 72 DPI took roughly 25–50 KB per page, so documents of about four or more scanned pages often can't fit in 100 KB at a readable resolution.

When the target is reached only below 72 DPI, the result is marked with a warning that small print may be hard to read. When it can't be reached at all, you still get the smallest file the tool could make and suggestions: remove pages you don't need with split PDF, send the document in parts, or ask whether a larger file is accepted.

Other targets: 200KB, 500KB, 1MB

Type any size into Target size (KB), for example 200, 500 or 1000 for 1 MB. Larger targets allow higher resolutions or let the text be kept. For stricter limits use compress PDF to 50KB; to choose the compression yourself instead of a size, use compress PDF. If your document is a set of photos, building the PDF with JPG to PDF and its Make the PDF smaller option keeps it small from the start.