Railway Recruitment Board applications now ask you for a single image, the signature, because the form takes your photograph live with the camera. The rule for that signature runs the other way from most exam forms. Bank and SSC notices cap a signature at 20 KB, while the railway notices set a floor of 30 KB, so the upload that bounces here is more often a tidy little strip that is too light than a phone photo that is too heavy.
This page holds both limits at once. It opens with 30 KB as the minimum and 50 KB as the maximum; the current notices stop at 49 KB, so change the maximum to 47 before you add the picture. The JPG quality is pushed up, and the picture enlarged when quality alone falls short, until the file clears the floor, and it is never allowed past the ceiling. What you download is a JPG.
How to use it
- Sign in your usual running hand with a black pen on plain white paper, not in capitals. Photograph the sheet flat in daylight, then crop loosely around the ink: a frame a little under twice as wide as it is tall matches the 35 × 20 mm box, and the 16:9 option in the crop tool comes very close.
- Type 47 in the maximum box if it still shows 50, and leave the ticked minimum at 30. Then add the cropped picture; it is processed straight away.
- Read two figures on the result: the weight should sit between 30 and 47 KB, and the pixel size should be at least 140 wide and 60 high. If a note on the card reports that the 30 KB floor was missed, the last question below explains why.
- Download the JPG and upload it at the signature step of the application. Should the portal object to the resolution, let the DPI converter record 200 DPI in the file; only a header changes, so the image data stays as it was and the weight grows by a few bytes at most.
What the railway notices say about the signature
Five recent notices from the Railway Recruitment Boards repeat one signature rule, figure for figure: CEN 02/2025 for Technician posts, CEN 06/2025 and CEN 07/2025 for NTPC graduate and undergraduate posts (in their application FAQs), CEN 09/2025 for Level 1 posts, the recruitment many people still call Group D, and CEN 01/2026 for Assistant Loco Pilot. The file must be JPG/JPEG only, with a file size between 30 KB and 49 KB and image dimensions of minimum 140 pixels (width) × 60 pixels (height). The signed paper is to be scanned at a minimum resolution of 100 DPI, and the signature should sit centred in a scan box of 35 mm (width) × 20 mm (height) on the application form.
The notices also list what gets an application rejected at any stage: a background that is not white, ink that is not black, a signature in block or capital letters instead of running handwriting, a blurred or partly visible signature, a thumb impression in its place, or someone else’s signature. Your signature is compared again at the exam, at document verification, at the medical and at appointment, so sign the way you will sign on those days. One inconsistency is worth knowing about: the FAQ published with CEN 09/2025 gives the signature as 30 KB to 70 KB. A file of 30 to 47 KB satisfies both readings.
Why 47 rather than 49? This tool reads 1 KB as 1,024 bytes, so 47 means at most 48,128 bytes, which is still below 49 KB on a server that counts a kilobyte as a round 1,000 bytes. At the other end, a minimum of 30 here means at least 30,720 bytes, safely above the floor under either reckoning.
Reaching 30 KB without breaking the rules
A JPG weighs what its detail costs to store. Clean white paper costs almost nothing and a signature covers only a small part of it, so a neat 140 × 60 strip comes to just a few kilobytes even at the highest quality. This page first raises the quality towards 100 and then enlarges the picture, but by no more than three times, which still leaves a strip that small well short of 30 KB. In the railway notices 140 × 60 is a minimum, not a target, and a larger file is perfectly acceptable; bank notices, which name 140 × 60 pixels as the preferred size, are a different case.
One shortcut, photographing the signature on grey or textured paper so the grain adds weight, runs straight into the first rejection ground on the list. Add pixels instead. Start from the original photo in your camera roll rather than a copy that has passed through a chat app, which shrinks it, and get close enough that the signature fills most of the frame before you crop. A white-paper signature cropped from a full-size phone photo is normally big enough, and because any enlargement is proportional, the shape you cropped to is kept.
Frequently asked questions
- What is the RRB signature size in KB and pixels?
- The file has to weigh from 30 KB up to 49 KB, be saved as JPG/JPEG, and measure no less than 140 pixels across and 60 pixels down. The Technician, NTPC, Level 1 and ALP notices all use these figures and add a scan resolution of at least 100 DPI. On this page, set the band to 30 and 47 to stay comfortably inside it.
- Should I resize the signature to exactly 140 × 60 pixels?
- No. The railway notices call 140 × 60 the minimum, and a strip that small is far too light for the 30 KB floor. Keep the picture larger and let this page settle the weight, then check on the result that neither side has dropped below those figures.
- What is the RRB signature size in cm?
- The notices do not size the image itself in centimetres. They describe a scan box on the application form of 35 mm (width) × 20 mm (height), or 3.5 by 2 cm, and ask for the signature to be centred in it. That box has a 7:4 shape, so a crop slightly less than twice as wide as it is tall fills it well.
- Is this the same as the IBPS RRB signature size?
- No. In IBPS RRB the letters stand for regional rural banks, and the IBPS CRP RRBs XV notice wants the signature from 10 KB up to 20 KB, sized 140 x 60 pixels (preferred). A 30 KB railway file would be refused there, so use the 10–20KB signature page for that form.
- Do I also need to resize a photo for the railway form?
- Not under the recent notices. They state that no pre-existing photograph is uploaded: the form captures a live photo through your webcam or the front camera of your phone, and a picture of a printed or on-screen photo is rejected. Wear dark clothes and take off glasses, cap or mask before the capture.
- The result says the 30 KB minimum could not be reached. What now?
- The picture holds too little detail even after the tool raised the quality to the top and enlarged it as far as it allows. That usually means it was small to begin with: a 140 × 60 strip, a screenshot, or a copy forwarded through a chat app. Go back to the original camera photo, or take a new one with the signature filling more of the frame, and crop that instead.