A wide document, not a photo
Unlike the photo, signature, and thumb impression fields, the handwritten declaration is a block of text — IBPS asks candidates to copy out a specific declaration sentence by hand, in English, in their own handwriting, then upload it as an 800 × 400 pixel image. That’s a 2:1 landscape ratio, wide enough to hold a full line or two of handwriting without cramming it down to illegibility.
Because it’s a landscape document copied from a mostly-landscape source (a sheet of ruled or plain paper, photographed or scanned lengthwise), it usually needs less aggressive cropping than the signature or photo fields — most people naturally write across the width of a page, which already roughly matches the 2:1 target shape. Still, this tool will centre-crop to exactly 800 × 400 if your source photo is a different ratio, so it’s worth photographing the declaration with a bit of margin trimmed close to the text itself, rather than including the whole sheet of paper.
Formatting reminders from the advertisement
IBPS’s guidance for this field (separate from the image spec itself) generally asks for the declaration to be copied out exactly as printed, without abbreviations, in the candidate’s own handwriting — check the current year’s advertisement PDF for the exact wording, since it can change between recruitment cycles. This tool only handles the image conversion: getting your photographed or scanned declaration down to 800 × 400 pixels and into the 50–100 KB range IBPS specifies for the file itself, with the same JPEG comment-block padding used elsewhere on this site if an honestly-encoded file comes in under the 50 KB floor.