Need a PDF under 100KB? Use the Compress PDF tool, pick Target size, and enter 100. The tool finds the strongest settings that fit under the limit and hands you the file — free, no signup, and the document never leaves your browser. That last part matters, because the files that hit 100KB limits are usually the sensitive ones: ID scans, bank documents, signed declarations.
Where the 100KB limit shows up
The 100KB ceiling is the strictest limit in common use, and it appears in exactly the places where documents are most personal:
- Banking and KYC portals. Identity verification uploads — passport pages, utility bills, signature specimens — frequently cap at 100KB per file.
- Government applications. Pension schemes, subsidy programs, and registration systems in many countries enforce 100KB or even 50KB per document.
- Exam and job applications. Photo and signature uploads for competitive exams often demand 20–100KB, with document attachments capped at 100–200KB.
These portals reject oversized files without explanation, and they're usually processing scans straight from a phone camera — which start at 2–5MB. That's a 95%+ reduction, and it's achievable for short documents.
How to do it
- Open Compress PDF. The target is prefilled at 100KB if you use this link.
- Drop your PDF onto the page. Nothing uploads — the file is read into your browser's memory only.
- Press Compress & download. The tool first checks whether a lossless pass already fits (if so, you keep selectable text). If not, it samples your pages at several resolution and quality levels, estimates the output size, and encodes at the strongest combination that fits under 100KB.
- Check the result panel. It shows the before/after sizes and the exact settings used. If 100KB genuinely wasn't reachable, it says so and gives you the smallest possible file instead of failing silently.
What "compressed to 100KB" means for quality
To get a scanned page from megabytes to kilobytes, the tool rebuilds each page as an optimized image. Two honest consequences:
Text is no longer selectable. The output is an image of your page. For portal uploads this is irrelevant — the reviewer looks at the document, they don't copy text from it. If you need a selectable-text version too, keep the original alongside the compressed copy.
Resolution drops. At 100KB, a single page lands around 72–150 DPI depending on content. That's comfortably legible on screen and acceptable in print for forms and IDs. Fine print on dense pages is the first thing to suffer, so always open the output and check it before submitting.
If 100KB isn't reachable
The floor for a legible page is roughly 15–40KB depending on content. Multi-page documents hit the wall fast: five pages can't go much below ~100–150KB. When the tool reports the target as unreachable, you have three options:
- Split first. Use Split PDF to break the document into single pages, then compress each — most portals accept multiple files.
- Submit only what's asked for. If the portal wants one bank statement page, don't upload the whole statement. Extract the page, then compress it.
- Rescan at lower resolution. If you control the scanner, 150 DPI grayscale produces dramatically smaller source files than 600 DPI color.
Why in-browser compression is the right call here
Every other "compress PDF to 100KB" site works by uploading your file to their server, compressing it there, and serving the result back. Their privacy policies promise deletion after an hour or a day — a promise you can't verify. The documents subject to 100KB limits are passports, bank records, and signatures: precisely the files you shouldn't hand to an unknown server.
PDF Cloak runs the same compression in your browser using open-source engines (pdf-lib and PDF.js). There is no server-side step to trust. Open your browser's developer tools, watch the network tab while you compress, and you'll see zero upload requests. Or load the page, switch to airplane mode, and compress offline — it works, because nothing about the process needs a network.