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PDFHive

Signature resizer

Turn a phone photo of your signature into a clean JPG for online forms: white background, cropped to the signature, at the exact size and KB limit the form asks for.

Your files are processed in your browser and never leave your device.

How to use Signature resizer

  1. Sign on plain white paper with a dark pen, take a photo, and click "Select signature photo".
  2. If the photo shows anything besides your signature, drag the box under "Signature area" around just the signature. Then choose a size (keep the signature's shape, 140 × 60 px, 3.5 × 1.5 cm, or your own) and how much white margin to leave around it.
  3. Check the KB limit (20 KB is filled in) and click "Resize signature".
  4. Compare the before and after pictures, then download the JPG.

How to make a signature background white

Photos of paper are rarely white: they come out grey or beige, with shadows from your hand or phone. PDFHive compares every part of the photo with the area around it, so shadows and uneven light become pure white while the ink stays as it is. Small specks of dust are removed too.

For the cleanest result, sign with a dark pen, take the photo in daylight or under a bright lamp, and hold the phone straight above the paper so the signature fills most of the picture.

How to get a signature under 20 KB

Signatures are mostly white space, so they compress very well. A signature at 140 × 60 pixels is usually only 3 to 4 KB, and even a large, sharp version about 900 pixels wide fits under 20 KB.

If a form also asks for a minimum size, such as at least 10 KB, choose a larger size in pixels: a bigger picture makes a bigger file.

What if your signature isn't found or looks faint?

The result depends most on the photo. These fixes solve nearly every problem.

  1. "No signature could be found": sign in dark ink on plain white paper, and photograph it in good light with the signature filling most of the picture.
  2. Faint or grey ink: tick "Make ink darker".
  3. A pen, a finger, a shadow or other writing is included in the crop: drag the box under "Signature area" around just the signature and click "Resize signature" again.
  4. Too big for the KB limit at an exact size: choose a smaller size in pixels, or "Keep shape", which can make the signature smaller to fit.

Frequently asked questions

Is my signature uploaded anywhere?

No. Your signature is cleaned and resized inside your web browser, on your own computer or phone. The photo is never sent to us or anyone else, which matters for something as personal as a signature.

Is the Signature resizer free?

Yes. It is free to use, with no sign-up and no watermark.

What size should my signature be?

Use exactly what your form says. 140 × 60 pixels and 3.5 × 1.5 cm are common requests, and you can type any other size. Centimetres are turned into pixels at 200 DPI. If a form gives both pixels and centimetres, use the pixels. Your signature is never stretched: if the shape differs, it is centred on white.

Can I turn a signature photo into a JPG?

Yes. Start from a JPG, PNG, WebP or iPhone HEIC photo or scan, and the result is always a JPG, the format online forms expect.

Will my blue ink stay blue?

Yes. The background becomes white but the ink keeps its colour. If your pen is faint, tick "Make ink darker": the ink gets deeper while staying blue or black.

Can I remove all the white space around my signature?

Yes. The empty paper is always cropped away. Under "Margin around the signature", choose None to crop right to the edge of the ink, Small for a thin border, or Normal for a little more room. If you pick an exact size whose shape differs from your signature, white space stays above and below or at the sides, because stretching the signature would distort it.

What if the crop includes something that isn't my signature?

Drag the box under "Signature area" around just your signature: anything outside it is ignored, and the signature is still cropped neatly inside it, so the box doesn't need to be tight. Lines that run through the signature itself, such as a ruled line on the paper, stay, because they are inside the box. For those, sign again on plain paper.

Does it work on my phone?

Yes. Take the photo with your phone, resize it here in the browser, and the JPG is saved to your phone ready to upload. iPhone photos are usually converted from HEIC to JPG automatically when you choose them.

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