Signature Resizer for Online Forms

The settings sit above the drop zone because every one of them is knowable before there is a file: they come off the form you are filling in. The rectangle is the exception and lives in the panel, because a crop means nothing until there is a picture to measure it against.

1. Type the size the form asks for. Width (px) and Height (px) sit above the drop zone, because both numbers come off the form rather than off the picture. Leave one side empty and it is worked out from the area you keep. The chips under them are examples only.
2. Choose the scan on your device. Drop a signature scan or photo onto the panel, or press Browse files. JPEG, PNG and WebP, up to 20 MB, read where it already sits — there is no transfer step.
3. Narrow the Area to keep down to the ink. The whole image is kept to begin with. Set X, Y, Width and Height under Area to keep and the outline over the preview follows you, dimming everything it is about to throw away. Select the whole image puts it back.
4. Pick the format and the ceiling. Save as gives you JPG or PNG, and Background — White or Black — decides what fills the space behind the ink when JPG cannot be transparent. Type a number into Maximum file size (KB) if the form names one, or leave it empty for no limit.
5. Press Make signature. If the crop is a different shape than the box you typed, the select of that name decides between fitting inside it, filling it and trimming the edges, or stretching to it. While a ceiling is being searched for the button reads Finding the size.
6. Read the line under the result, then Download signature. It names the size and the byte count you finished on, the region that was kept, and whether the dimensions had to change to meet the limit. Press Download signature once those figures match what the form asked for.

A scan of a signature is mostly paper. The strokes might occupy a fifth of the frame, and every other pixel is margin that still has to be stored, still has to be scaled and still spends part of whatever file size limit the form set. Trimming to the ink is usually the single largest saving available on this page, and it costs nothing.

It also changes what the size means. The width and height you type are applied to the area you kept, not to the original scan, so margin left inside the selection becomes margin inside the finished box — ask for 300×80 around a generous crop and the signature itself arrives at half that, looking thin and faint in a field sized for it.

The whole image is kept when a file lands, so narrowing it is an edit rather than a required step. Set X, Y, Width and Height under Area to keep and the outline moves over the preview, dimming the part that goes; the line above the fields reads back what you have described as Keeping, with the corner it starts from. Select the whole image restores everything if you go too far. The cropper is the better page when the picture is not a signature and you only want a rectangle out of it — it has aspect-ratio chips and no size or byte fields to fill in.

Type both numbers when the form gives both. Leave one side empty and it is worked out from the area you kept, which keeps the signature in its own proportions — a 200 px width asked of a 400×120 selection comes back 200×60.

A signature is wide and short, and the box a form names rarely shares that shape. That is genuinely ambiguous, so the select labelled If the crop is a different shape asks you rather than guessing:

• Fit inside the size (no distortion) is the default. The selection is scaled until all of it sits inside the box, so one side can come back smaller than the number you typed. Nothing is cut off and nothing is squashed.
• Fill the size and trim the edges gives you both numbers exactly, and pays for them by scaling until the box is covered and cutting the overflow off the middle. Safe when the crop is close to the right shape already, and expensive when it is not.
• Stretch to the exact size (distorts) resamples straight to the box, so handwriting comes out visibly squashed or drawn out. It exists for a field that checks the dimensions and nothing else, it is never the default, and the result says Stretched to the exact size you chose so nobody discovers it later.

Fitting is also allowed to enlarge, so a small crop is scaled up to reach the box and the strokes soften as it goes. If the result looks woolly, the answer is a bigger scan rather than a different setting. And the neatest way to land on both of the form’s numbers is to crop close to the shape it asked for in the first place. Resizing an ordinary photo is a different job with different controls — a percentage, one side, or a full pixel box.

Before

After

Ink on paper is two tones doing nearly all the work, which is the picture PNG is best at: it stores runs of identical colour exactly, so a tightly cropped signature often lands in a couple of kilobytes with every stroke where it was drawn. JPG approximates instead, and approximation is worst against a hard edge — the grey halo around each stroke at low quality is the encoder guessing at an edge it cannot afford to store.

So PNG is the better default for this particular kind of picture, and the form still outranks it. Save as offers JPG and PNG because those are the two that signature fields accept; if yours names one, that is the one.

Background — White or Black — only applies to JPG, which has no transparency to keep, and the radios grey out the moment PNG is selected. White is the default because a signature is going onto a document. What neither setting does is remove anything: this page will not lift the ink off its background, so a photograph of white paper stays a rectangle of pale pixels whichever format you choose.

Maximum file size (KB) is the ceiling, and leaving it empty means no ceiling at all. The box is reached first and the ceiling is spent afterwards, which is the order that matters: the dimensions are what the form checks by eye, so they are the last thing given up.

For a JPG, quality comes down first and stops at 50, because below that the blocking and ringing become visible on a document. Only if 50 is still over the line does the picture start shrinking, at four fifths of each side per step, up to eight steps and never below 32 pixels on the short side. A PNG has no quality dial at all — the encoder here is lossless — so a PNG under a tight ceiling goes straight to losing pixels.

None of that is silent, and that is the point of the page. The line under the finished picture reads either Dimensions were not changed to meet the size limit, or a sentence naming the size it was shrunk from and the size it ended on. A form that asked for 300×80 will not take 240×64, and you cannot see the difference in a preview — being told is the only way to find out before the form does.

Ceilings from 10 KB up to 20 MB are accepted, and anything outside that says so under the field. While the search runs the button reads Finding the size, because it is encoding the picture repeatedly and measuring what actually came out rather than estimating. Compress it to 20 KB is the page to use when the crop and the pixels are already right and only the number is wrong.

JPEG, PNG and WebP, up to 20 MB per file; the finished signature can be at most 8000 pixels on a side, and a scan too large for what this device can hold in memory is refused before it starts, with the reason. An iPhone picture still in HEIC is not one of those and has to be converted before it can be cropped here — turn it into a JPEG first and then come back.

It crops, scales, fills the space behind a JPG and encodes. It does not remove a background, separate ink from paper, clean up a shadow or a crease, sharpen a blurred stroke, or redraw a signature as a vector. If a form wants a clean signature, the cheapest fix by a wide margin is a better scan: black pen, white paper, flat and evenly lit. Stripping the metadata is the separate job to reach for when the picture itself is already right and you only want the camera and scanner fields out of the file.

All of it happens on your own device. The scan is opened where it already sits, the rectangle is cut, the pixels are resampled and the new file is written on the same machine, so nothing is transmitted and no copy of your signature exists anywhere else. Because the output is built from raw pixels it carries no EXIF or GPS data either.

The one limit that belongs to you rather than to us is memory. A picture has to be unpacked into raw pixels before any of this can happen, which takes several times the file size, and a byte ceiling means encoding it several times over — so the panel costs the job before it starts and refuses it with a reason rather than letting the tab die holding your only scan.