Resize your signature to 20 KB

A signature is the easiest file to get wrong

Forms reject signatures for reasons that have little to do with the signature: the file is 3 KB and the minimum is 10, the paper came out grey, the signature is a tiny scribble in the middle of a big white image, or it is a PNG when the form wants a JPEG. This page is set up to avoid all four.

What happens to the photo

The paper turns white. Clean up paper finds the split between ink and paper from the photo's own brightness (Otsu's method) and turns everything lighter than the paper level pure white. The ink keeps its colour, pushed darker so it survives heavy compression.

The box frames the ink. When clean-up is turned on, the crop box moves and zooms to the signature itself, with a small margin, in the shape the form wants. Drag it if you want it placed differently.

The size is exact. 140 × 60 pixels at 200 DPI is the size the SBI PO and SBI Clerk notices give for the signature. Other forms differ: SSC asks for about 6.0 × 2.0 cm, CTET 3.5 × 1.5 cm, India Post GDS 300 × 120 pixels. Change it under Dimensions, or open the exam pages, which are preset from each notice.

It lands between 10 and 20 KB. Above 20 KB, the quality is lowered until it fits. Below 10 KB, empty bytes are added inside the file. 20 KB is read as 20,000 bytes and 10 KB as 10,240, so the file passes however the portal counts.

Taking the photo

Sign on plain white paper with a black or blue pen, a little larger than your everyday signature, so it does not turn into a thin scribble when shrunk. Photograph it in daylight, phone held flat above the paper so the signature is not skewed, with no shadow from your hand or phone. Fill most of the frame with the paper.

Avoid lined or squared paper; the lines survive clean-up and look like part of the signature. If you can only find a pale pen, press harder; faint strokes can break up at small sizes.

Check the file before the form does

Open Check a file and drop the JPG you are about to upload. It shows the real format, KB and pixels against your rules and marks each one pass or fail. If one fails, Fix it sends the file back here.

Thumb impression and declaration

Some forms want more than a signature. The SBI notices ask for a left thumb impression at 240 × 240 pixels (3 × 3 cm at 200 DPI), 20–50 KB, in black or blue ink on white paper, and a handwritten declaration at 800 × 400 pixels (10 × 5 cm at 200 DPI), 50–100 KB. The same clean-up works for both. The SBI PO page has all four uploads preset.