Compress PDF to 100 KB

Exam registrations, government services, scholarship and job portals often accept a PDF of at most 100 KB — far smaller than a phone scan of a certificate. This tool keeps shrinking your PDF until it fits: first without any loss, then by recompressing its images, and only if you allow it by turning the pages into compact images. It runs in your browser, so ID cards and certificates never leave your device.

How to use this tool

1. Choose the PDF (or several).
2. Keep the target at 100 KB or type the limit the website states, such as 50 or 150 KB.
3. Leave “turn pages into images” on unless the text must stay selectable; tick Grayscale if colour isn’t needed.
4. Download the result and check the reported size, method and whether the target was reached.

Formula

Target in bytes = KB × 1,024. Passes run in order — lossless clean-up, then images at 150 → 40 DPI, then pages as images at 150 → 30 DPI. In each image pass the tool finds the highest resolution that still fits, then raises the JPEG quality by halving the interval, keeping the best quality that fits.

Quality is first kept between 50% and 85%; only if nothing fits does the search go down to 20%. Many portals count 100 KB as 102,400 bytes; if yours means 100,000 bytes, enter 97.

Example

A two-page scanned mark sheet of 1.8 MB with a 100 KB target typically ends up at about 90–99 KB after the image pass at around 80–100 DPI, still readable on screen. A five-page colour scan may need the page-image pass at about 65 DPI, or grayscale.

Why some files can’t reach the target

Every page needs some bytes, so very long documents cannot fit a tiny limit and still be readable. When the target can’t be reached, you get the smallest version found and the reason. Upload portals usually need one or two pages, so split off just the pages you need first with Split PDF or Extract PDF Pages.