UPSC OTR Spec

Compress PDF for UPSC.

Prepare your certificates for UPSC registration. Shrink documents to the strict 300 KB limit directly on your device — no uploads, no privacy risk.

Compress to 300 KB

UPSC CSE / OTR upload specifications

DocumentFormat & Size
Certificate/Document PDF Size20 KB to 300 KB
Candidate Photograph (JPG)20 KB to 200 KB
Candidate Signature (JPG)20 KB to 200 KB
File FormatPDF Only (for certificates)

Last verified: 2026-08-03

UPSC Document Upload Requirements.

The Union Public Service Commission (UPSC) enforces strict size limits on PDF certificates, such as reservation category proofs, age relaxation certificates, and educational documents.

Under the UPSC One Time Registration (OTR) system, scanned PDF certificates must be not less than 20 KB and not exceed 300 KB. Files outside this range are rejected by the server.

We recommend targetting around 250 KB to prevent decimal/binary size mismatches (300 KB vs 300 KiB) that often lead to unexpected upload rejections.

How to name files for UPSC.

UPSC's system is highly sensitive to naming conventions. Avoid using special characters, spaces, or uppercase letters in your file name.

Format your filename clearly, for example: 'caste_certificate.pdf' or 'matriculation_proof.pdf'. This ensures maximum compatibility and prevents portal errors.

Your files stay on your device.

Your document never leaves your browser. Compression runs 100% client-side using browser APIs — no server uploads, no data collection, no account required.

Frequently Asked Questions.

UPSC requires scanned document PDFs to be between 20 KB and 300 KB. Any file larger than 300 KB or smaller than 20 KB will fail to upload.
Yes, our custom compression slider allows you to target 300 KB. However, we recommend selecting 250 KB. The visual difference is indistinguishable, and you guarantee your file stays safely below the server's byte cap.
UPSC servers calculate file size using binary bytes (1 KB = 1024 bytes). If your operating system reports 299 KB (decimal), the file might actually be 306,000 bytes, which exceeds UPSC's 307,200 byte limit. Setting a target of 250 KB ensures your file passes both binary and decimal validation.
Yes, 100% safe. Zcompressor uses browser-native WebAssembly APIs. Your PDF certificates are processed entirely inside your computer or smartphone's memory. No file is ever uploaded to external servers or logged in a database.
Certificates (such as Caste, PwBD, Matriculation, or Age proof) must be uploaded in PDF format only. Photographs and signatures must be uploaded in JPG/JPEG format.
After compressing, open the downloaded PDF and zoom in to 100%. Check that your name, registration number, date of birth, issuing authority stamp, and signature are clear and legible before uploading to the UPSC OTR portal.

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