RRB signature size: official rules
Sources: RRB CEN 09/2025 (Level 1 / Group D), CEN 01/2026 (ALP) and CEN 06/2025 (NTPC Graduate). Read the CEN for your post before uploading; RRB rules can change between notifications.
How to resize your signature for RRB
- Sign on plain white paper with a black pen, in your normal running hand, not in capitals.
- Photograph it from straight above in good light. The table around the paper is removed automatically.
- Choose the photo above. Min 30 KB, Max 49 KB and 200 DPI are already set.
- Optionally tap RRB box 35×20 mm so the image has the same shape as the box on the form. The signature is fitted inside with a white border and is never cut off.
- Download the JPG and upload it.
How the tool reaches 30 KB
A clean black signature on white paper is mostly empty space, and empty space compresses to almost nothing. At 140×60 pixels it is usually 3–6 KB, far below RRB's 30 KB minimum. The tool handles this in two steps. First it keeps more pixels, so the strokes are sharper and the file is naturally larger. If the file is still under 30 KB, it adds padding bytes inside the JPG, which every image viewer and upload checker ignores. The signature looks exactly the same; only the file size changes.
On the other side, the maximum is 49 KB, not 50. The tool keeps the file under 49,000 bytes, so it passes even if the portal counts 1 KB as 1000 bytes.
RRB signature on a phone, step by step
Put a blank white sheet on a table near a window, sign it with a black ball pen, and hold the phone directly above so the paper looks rectangular. Tap the screen on the ink to focus, then take the photo. Open this page in the phone's browser, choose the photo and wait a second: the tool cleans the paper, cuts the margins and shows the exact size, for example 41.2 KB (42,190 bytes). Download it, and in the RRB form choose the file from Downloads on Android or Files on iPhone. If the preview looks faint, raise Contrast a little and the tool redoes the file inside the 30–49 KB range.
Why RRB rejects signatures
- Background not white. Grey paper, a shadow or a coloured page. The clean-up turns paper pure white.
- Ink not black. Blue or coloured ink can be rejected under RRB rules.
- Block or capital letters. Sign the way you sign a cheque.
- A thumb impression instead of a signature. The notices list this as a reason for rejection.
- File outside 30–49 KB. Both too small and too large are rejected.
RRB live photo
RRB no longer asks you to upload a photo. The application captures one through your webcam or phone's front camera. The notices ask candidates to wear non-white, preferably dark clothes, to avoid caps, masks and glasses, and not to photograph a printed or on-screen photo. For ALP 2026, if the live photo cannot be matched, the candidate may have to upload a form signed by a Gazetted Officer, so take the live photo carefully in good light.
Other RRB uploads
SC and ST candidates who claim the free railway travel pass for the exam upload their caste certificate as a PDF under 400 KB; this tool creates JPG images, so use a PDF compressor for that file. No other photo or document upload is needed at the application stage in the notices we checked.
Old RRB rules you may still see online
Before the switch to live photos, RRB notices such as ALP CEN 01/2025 asked for an uploaded photo of 50–150 KB, 35×45 mm, at least 240×320 pixels and 150 DPI, with a white background and dark clothes. Many websites and videos still quote those numbers, or a "20–70 KB, 320×240" rule that does not appear in the notices. For current RRB applications the photo is captured live; only the 30–49 KB signature needs to be uploaded.
Other signature rules
SSC uses 10–20 KB at about 6×2 cm; see SSC signature size. Bank exams use 10–20 KB at 140×60 pixels on the signature resize page. For a plain size limit without clean-up, use resize image to 50KB.
Frequently asked questions
What is the RRB signature size?
Recent RRB notices (Group D CEN 09/2025, ALP CEN 01/2026, NTPC Graduate CEN 06/2025) ask for a JPG/JPEG signature between 30 KB and 49 KB, at least 140×60 pixels, scanned at 100 DPI or more.
Why is the RRB signature minimum 30 KB?
RRB sets a higher minimum than other exams, probably so the signature is detailed enough to verify. A clean signature is often only a few KB, so it must be kept larger or padded to reach 30 KB. This page does that automatically.
Can I sign in capital letters for RRB?
No. The notices ask for a running (joined-up) signature and say signatures in block or capital letters are not accepted.
Does RRB need a photo upload?
No. RRB captures a live photo through your webcam or phone during the application. You should wear non-white, preferably dark clothes and no cap, mask or glasses.
My signature file is 49.5 KB on my phone. Is that OK?
It may fail. 49.5 KB on a phone can be 50,688 bytes, which is over a 49 KB limit counted in 1000 bytes. Files from this page stay under 49,000 bytes.
Does the RRB signature need a DPI value?
The notices ask for a scan of at least 100 DPI. This page writes 200 DPI into the file by default, which meets that rule even if the portal reads the DPI.
Is my signature stored anywhere?
No. It is processed in your browser and never uploaded.