Signature Resizer
Crop a photo of your handwritten signature to a clean strip, whiten the paper background, and export an exact pixel size at or under a KB cap — all in your browser. Nothing is uploaded.
Click or drag a signature photo here
JPG or PNG · the file stays on your device
Crop, clean and size a signature for any form
A scanned or photographed signature is almost never ready to upload. It has a grey cast from the paper, a wide margin around the ink, and a file size set by the camera rather than by the form. This tool fixes all three in one pass: drag the box to frame just the signature at a strip ratio, push the near-white paper to pure white, then export at the exact pixel size the form asks for.
The white threshold sets the luminance at and above which a pixel counts as paper; the strength slider decides how hard those pixels are pushed toward white, ramped over a narrow band so the ink edge stays smooth instead of stair-stepping. Ink below the threshold is never altered, so the stroke keeps its shape and anti-aliasing.
Export is plain JPEG plus a binary quality search: the encoder tries quality levels between 0.10 and 0.95 and keeps the highest one whose file still fits your KB cap, so you get the sharpest signature that still passes the portal check. If the cap cannot be reached at that pixel size the tool says so and hands you the smallest file it can make.
Privacy: the image is read with Canvas in your browser and is never uploaded, stored or transmitted. There is no server and no account.
What the forms actually ask for
There is no single universal size for a signature: the form sets the rule. Where an official figure exists, it is usually a file-size cap rather than a pixel size, which is exactly what the KB box above is for.
| Form / portal | What it requires | Source |
|---|---|---|
| India — OCI registration | Photograph and signature must be JPEG/JPG, maximum 200 KB (the same limit applies to both) | ociservices.gov.in FAQ / mea.gov.in FAQ |
| Most other forms | A strip of fixed pixels and a KB cap stated on the form itself — read the upload box rather than assuming a standard | the form you are filing |
The presets in the tool are starting points, not an official standard: a 3.5 × 1.5 cm strip is 413 × 177 px at 300 dpi or 827 × 354 px at 600 dpi, a 2 × 0.6 in strip is 600 × 180 px at 300 dpi or 1200 × 360 px at 600 dpi, and there is a 140 × 60 px preset for India-style forms. If your form states exact pixels, type them; if it states only a KB cap, crop and whiten first, then let the KB search finish the job.
Where a signature sits in a document checklist
Signature images rarely travel alone — they are one attachment among many on a visa or passport application. The country checklists gather the rest: the India visa documents checklist and the US visa documents checklist both cover the full set of uploads, and the checklists hub has every country. If an upload was refused for size or format rather than for the signature itself, work through the digital file requirements, and validate any photo you send alongside it with the passport photo checker.
Frequently asked questions
Is my signature uploaded anywhere?
No. The crop, the whitening pass and the JPEG encoding all run in your browser with Canvas. The image never leaves your device, and there is no server or account.
What size should a signature image be?
It depends on the form. A common print strip is 3.5 × 1.5 cm, which is 413 × 177 px at 300 dpi or 827 × 354 px at 600 dpi. Many portals instead cap the file in KB and let the pixel size follow. Pick a preset or type exact pixels, then set the KB cap if the form states one.
How does the background whitening work?
Pixels whose luminance is at or above the threshold you set are pushed toward pure white by the strength you choose; the band just below the threshold is ramped so ink edges stay smooth. Ink darker than the threshold is left untouched, so the stroke shape is preserved.
How do you hit a maximum file size in KB?
The tool re-encodes the JPEG at a series of quality levels between 0.10 and 0.95 and keeps the highest quality whose file still fits your cap. If even the lowest quality is above the cap at that pixel size, it tells you and returns the smallest file it can produce.
Does it work on phone photos of a signature?
Yes. A phone photo works as long as the ink is reasonably dark and the paper is lighter than the threshold. Frame tightly with the crop box for the best result, and raise the threshold a little if the paper looks grey.
Is it free?
Yes. The signature resizer is free and runs entirely on your device, with no watermark and no sign-up.
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