How to compress a PDF to under 100 KB
Job portals, government forms and email gateways love hard limits — “attachment must be under 100 KB” — and most PDFs are nowhere near that. Here's how to actually hit a tiny target, privately, without uploading the document to anyone's server.
Step by step
- Open the Compress PDF tool. Everything runs in your browser — the document (often a CV, ID scan or signed form, i.e. exactly what you don't want on a stranger's server) never uploads. Drop your PDF in.
- Start with the Extreme preset. For a small target like 100 KB, skip Balanced and go straight to Extreme. It renders pages at a lower resolution with stronger JPEG compression — usually a 70–90% reduction.
- Switch to grayscale if you're still over. Color is expensive. The Grayscale mode cuts another 20–40% and is perfectly acceptable for forms, CVs and scanned text.
- Fine-tune with Custom. If you're close but not under, pick Custom and pull Resolution down to ~90 DPI and quality toward 35–45%. Text stays readable well below the point where photos get ugly.
- Check the result and iterate. The before/after sizes show immediately. Re-run with harsher settings if needed — each attempt takes seconds because there's no upload round-trip.
Worth knowing
If the PDF is one page and still won't fit, the page probably contains a huge photo — crop it first (Crop PDF) or split off just the page they actually need (Split PDF). And if a form portal demands under 100 KB for a multi-page scan, submitting pages as separate files is usually allowed — Split PDF does that in one click.
Frequently asked questions
Will the text still be selectable after compression?
No — heavy compression rebuilds pages as images, which is how the big savings happen. For a size-limited upload that's almost always fine; keep your original for editing.
Why not use an online compressor with a server?
You'd upload the document (slow), trust them with it (why?), and often hit a paywall for “extreme” presets. Client-side compression has none of those problems.