"The file you uploaded exceeds the maximum size." If you've dealt with government or admission portals, you've seen it. Here's why PDFs balloon in size, and how to bring any document under a limit without it becoming unreadable.
Where a PDF's size actually goes
A PDF that feels simple can be surprisingly heavy. The usual culprits are scanned pages stored as full-resolution colour images, embedded fonts, and images saved at print DPI when screen DPI would do. A single colour scan of an A4 page can easily be over a megabyte on its own. Upload portals, though, don't need print quality — they need a legible document a reviewer can read on screen. The gap between those two is the room you compress into.
How PDF compression works
Strong compression re-renders each page at the lowest resolution that still looks clean, and stores it efficiently. FileKitt's PDF compressor targets an exact size: you set the ceiling, and it finds the highest fidelity that stays under it. The important trade-off to understand is that aggressive compression converts pages to images, so the text is no longer selectable in the output. For an upload that's irrelevant — but keep your original if you'll need to edit or search the document later.
Choosing the right target
- 100 KB — the strictest common limit, seen on single-page certificate and ID uploads. Realistic for a short text document; hard on colour scans. See the 100 KB tool.
- 200 KB — the most common cap of all, standard on KYC, visa and admission portals. Comfortable for a few text pages or a single scan. See the 200 KB tool.
- 500 KB — roomy enough for multi-page scans and longer contracts without softening text. See the 500 KB tool.
A workflow that avoids repeat rejections
- Assemble first. If the portal wants one PDF containing several documents, merge them before compressing — compressing the combined file gets you under the limit more reliably.
- Compress to the stated limit, not lower. Over-compressing only costs you legibility.
- Open the result and read it before uploading. Ten seconds here saves a rejected submission.
- Keep the original for your records and for any future editing.
If your PDF is a scan
Scanned PDFs are the heaviest and the hardest to shrink cleanly. If you control the scan, capture it in grayscale at a moderate resolution rather than full-colour high DPI — you'll start far smaller and have to compress far less. And if the file is password-protected, remove the password first (open it, then print-to-PDF), because encrypted PDFs can't be processed.
Privacy matters here too
The documents people compress for portals — bank statements, IDs, contracts — are exactly the ones you shouldn't upload to an unknown server. Because FileKitt compresses in your browser, nothing is transmitted anywhere, so sensitive paperwork stays on your machine.