RRB’s centralized application system — used for NTPC, Group D, ALP, and most other Railway Recruitment Board postings — has a document upload step that catches people off guard in a specific way: it’s not that the limit is confusing, like JoSAA’s tiered figures or IBPS’s five different fields. It’s that the number is genuinely tiny. Candidates who’ve already cleared NSP or CUET’s 200KB certificate caps assume they know what “small” means, then watch RRB reject a file that’s already a fraction of that.
Short version: across RRB’s NTPC, Group D, and ALP notifications, the photograph runs 50-100KB (JPEG, roughly 320×240px), the signature runs 30-50KB (JPEG, 140×60px), and certificate PDFs — category, PwBD, scribe, and other supporting documents — are capped at just 10-40KB. That last figure is the tightest limit on any government portal covered on this site, and it needs a deliberate approach, not a one-tap preset.
What RRB’s applications actually specify
These figures are drawn from RRB’s own document-upload guidance — published per-zone, such as rrbbnc.gov.in’s uploading-documents notice — and echoed consistently across independent exam-prep trackers like Oliveboard and ExamFormTools.
| Document | Format | Dimensions | Size |
|---|---|---|---|
| Photograph | JPEG | 320×240px (or 35×45mm), min 100 DPI | 50-100 KB |
| Signature | JPEG | 140×60px, min 100 DPI | 30-50 KB |
| Scribe’s photograph (PwBD candidates using a scribe) | JPEG | Same as candidate photo | 50-100 KB |
| Certificates (category, PwBD, and other supporting documents) | — | 10-40 KB |
RRB’s own notifications also specify the signature must be signed inside a marked 35mm × 20mm scan box, in running handwriting, not capital letters — a formatting detail worth knowing since it’s a rejection cause a compressor can’t fix. For the photo and signature images themselves — separate JPEG uploads, not PDFs — Resize Photo & Signature has an RRB/Railway preset built to these exact dimensions and KB ranges.
Why a 10-40KB certificate is genuinely different
Every other portal covered on this site — NSP, CUET, DU CSAS, even the general “under 1MB” fallback — sits somewhere between 200KB and 1MB. RRB’s certificate cap is an order of magnitude tighter than the loosest of those and still noticeably tighter than NSP’s already-strict 200KB. That changes what actually works:
A preset chip built for 200KB won’t get you there. Compress PDF’s one-tap presets target NSP/CUET (200KB), DU CSAS (300KB), and JoSAA (500KB) — none of them land anywhere near 10-40KB. Skip the presets and type your exact number — 30 or 35KB, say — into the custom target field instead.
Every extra byte of scan quality matters more here than anywhere else on this site. At a 200KB target, a slightly noisier scan barely changes the outcome. At 30KB, the gap between a clean, high-contrast scan and a slightly gray or skewed one can be the difference between a legible seal and a blurry one — because there’s so little byte budget left to absorb bad source material.
A multi-page or dense certificate may not clear this at all. A one-page category certificate with a clean stamp usually has enough headroom. A certificate with dense small print, or more than one page, is fighting a genuinely tight ceiling — and this is the target on this site most likely to hit that wall.
How to hit the exact number
- Scan the certificate at a moderate setting, in good contrast light — not for print quality, since it’s getting compressed to a fraction of a typical scan regardless. A flat, well-lit, black-on-white scan gives the compressor far more room to work with than a shadowed or slightly angled one.
- Open Compress PDF, upload the document, and skip the preset chips. None of the four one-tap presets target this range. Use the custom target field below them and type your exact number — check your specific CEN notification first, since RRB’s stated figure has varied slightly between recruitment cycles and between NTPC, Group D, and ALP.
- Aim for the middle of the range you’ve been given, not the very top. If your notification states “up to 40KB,” typing 35 leaves a small margin for a file that grows by a few hundred bytes after download, without giving up much visible quality compared to targeting 40 exactly.
- The tool renders the page, re-encodes it as JPEG at a searched quality level, and steps resolution down too if quality alone can’t reach the target — the same mechanism used for every other target on this site, just working from a much smaller byte budget.
- Zoom into the result before uploading. At this target size, checking the seal, registration number, and any small print isn’t optional — it’s the step most likely to catch a certificate that technically hit the number but isn’t actually readable.
Everything runs in your browser via JavaScript — nothing about a category or PwBD certificate gets sent to a server to be compressed.
If a certificate won’t clear 10-40KB
This is the target on this site most likely to hit a real floor. If Compress PDF can’t get a document down to your number without the seal or registration number turning illegible, that’s the tool telling you something true, not failing — a 10-40KB budget for a scanned page of any real detail is close to the physical limit of what a rasterized image can hold and still be readable.
If you hit that wall:
- Rescan instead of re-compressing. A cleaner, flatter, higher-contrast scan gives the compressor meaningfully more to work with at this budget than a slightly better compression pass on a mediocre scan ever will.
- Check whether the certificate can be split or cropped tighter first. A category certificate with a wide blank margin or a letterhead block you don’t need is spending part of your 10-40KB budget on content nobody’s checking — Crop PDF trims that before compression runs.
- Confirm the exact figure for your specific notification. RRB’s certificate cap has been reported differently across cycles and postings — check the current CEN notification before assuming last cycle’s number still applies.
If you’re also applying through a banking or SSC exam
RRB’s tight certificate cap is unusual even among Indian government exams — most other bodies run closer to 200-500KB. If you’re also handling an SSC, UPSC, or IBPS/banking application alongside a railway one, don’t reuse the same aggressively-compressed file across all of them: Compress PDF for UPSC and SSC Forms and Compress PDF for IBPS and Bank Exam Applications cover those looser, more typical ranges — a file compressed hard enough for RRB is smaller than either needs, but check the dimensions and format each one specifically asks for before reusing anything.
Start with the custom target field in Compress PDF, type the exact figure your CEN notification states, and check the result at zoom before you submit.