Why 300 KB specifically.
300 KB isn't a generic marketing number — it's the actual upper limit UPSC sets for certificate PDF uploads in its One Time Registration (OTR) system. When candidates search for 'compress PDF to 300 KB', they're usually holding a UPSC notification that specifies this exact figure.
Other portals that use 300 KB limits include certain state public service commission applications (APPSC, TSPSC) for individual certificate uploads. If a portal tells you '300 KB max', this is the tool.
What a 300 KB PDF looks like.
A typical scanned certificate starts at 3–4 MB (a single colour page at 300 DPI). Compressing to 300 KB means reducing to roughly 8–10% of the original file size. At this ratio:
• Text remains legible — names, dates, certificate numbers, and registration IDs are clearly readable.
• Official seals and stamps are visible, though fine watermark lines may lose some detail.
• Photographs embedded in the certificate (like a passport photo on an ID proof) retain enough clarity for verification.
• The PDF will have slightly softer image quality compared to the original scan, but this is expected and accepted by portals.
The 300 KB vs 300 KiB confusion.
This is genuinely the most common reason uploads get rejected. Here's why:
300 KB (decimal) = 300,000 bytes. 300 KiB (binary) = 307,200 bytes. Some portals measure one way, some measure the other, and they both display as '300 KB' in the requirement.
If your file is 301,000 bytes, it's over 300 KB but under 300 KiB. Depending on which system the portal uses, it may pass or fail.
Our recommendation: target 250 KB. The visual quality difference between 250 KB and 300 KB for a scanned certificate is negligible, and you eliminate the binary/decimal ambiguity entirely.
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Your document never leaves your browser. Compression runs 100% client-side using browser APIs — no server uploads, no data collection, no account required.