Compress a PDF to 100 KB

100 KB for a scan

At 100 KB, a one- or two-page certificate fits comfortably if the pages are mostly white paper with printed text. A full-colour, full-page photo of a document fits too, but at a lower resolution. This page starts in Black & white, because for documents that is the setting that keeps text sharp at small sizes.

How it works

Each page is drawn at 150 dpi, saved as a JPEG, and the PDF is rebuilt and measured. The quality moves up or down until the file is the best it can be under 100,000 bytes. If that is not possible at 150 dpi, it steps down to 110, 90, 72, 60 and 50 dpi. The result shows the resolution and quality used, so you can judge whether the text will still be readable.

Get more out of 100 KB

Scan flat and bright. Shadows and grey paper cost bytes. A scan with white paper compresses far better than a dim photo.

Crop to the page. A photo of a document on a desk includes the desk. Crop to the paper in your scanning app first.

Only the pages they ask for. Every extra page shares the same 100 KB.

Limits

Up to 20 pages. Password-protected PDFs need the password removed in your reader first. Pages become pictures, so text in the new PDF cannot be selected.

Need more room? The 200 KB page uses the same tool with a bigger limit.

Reading the result

The result shows the size, pages, resolution and JPEG quality. 150 dpi and quality above about 30% read like the original on screen. If the tool had to go down to 72 dpi or below, zoom in on the smallest text before you upload. If that is hard to read, remove pages you do not need or ask whether the portal allows 200 KB.

When to switch to colour

Keep Black & white for printed text, marksheets, ID cards and most certificates. Switch to Colour when the reviewer has to see something only colour shows: a coloured seal or stamp, a coloured photo on the document, or a signature in blue ink that the form says must be blue.

If it already fits

When the original PDF is already under 100 KB, the page says so before you press anything, and you can upload it as it is. Making it again would only lower its quality, and your original keeps its selectable text.

What the portal checks

Portals look at the file type and the size, sometimes the page count. A PDF whose pages are pictures is exactly what a scanning app produces, so it is accepted wherever scans are.