How to add a signature to a PDF or Word document

You need two things: a clean image of your signature, and a program that can place an image on the page. Most people already have both.

Updated 9 October 2026 · 6 min read

Step 1: get a signature image

Every method below works best with a PNG that has a transparent background. The signature then sits on the signature line without a white box around it, which matters on forms with coloured fields, lines or a grey background.

• Draw it: open the signature maker, sign with your mouse, trackpad, finger or stylus, and press Download PNG. The download is trimmed to the signature, with a transparent background.
• Type it: switch to the Type tab, enter your name and choose a script font. This looks neat but is clearly a typed name, which some people prefer for informal documents and others avoid.
• Use your real pen signature: sign on paper, photograph it and remove the background. See how to make a transparent signature PNG for the details.

Dark blue or black ink reads best on screen and in print. Keep a copy of the PNG somewhere private, such as your own device, rather than in shared folders. Anyone who has the file can paste it onto a document.

Sign a PDF

Adobe Acrobat Reader (Windows and Mac, free)

1. Open the PDF in Acrobat Reader and choose the Fill & Sign tool (in newer versions it is listed under All tools).
2. Choose to sign yourself and add a signature. Acrobat offers Type, Draw and Image; pick Image and select your PNG.
3. Click where the signature should go, then drag the corner to resize it.
4. Save the file. Acrobat can remember the signature for next time if you leave that option ticked.

The exact labels move around between Acrobat versions, but the tool is always called Fill & Sign, and the free Reader includes it.

Preview on a Mac

Preview has its own signature tool. Open the PDF, show the Markup toolbar, and click the signature button. You can create a signature by signing on the trackpad or by holding a paper signature up to the camera. Preview stores it, and you can drop it on any PDF afterwards. Preview's signature tool works from the trackpad or camera rather than from an image file, so if you want to use a PNG you made elsewhere, Acrobat Reader is the simpler route.

iPhone and iPad

Open the PDF in the Files app or from a Mail attachment, tap the Markup (pen) button, then the + button and choose Add Signature. You sign with your finger on the screen and the signature is saved for reuse. You can also add an image from the same + menu in some apps, but the built-in signature is usually quicker.

Android

Android does not have one standard PDF editor, so it depends on the phone. The free Acrobat Reader app for Android has Fill & Sign and works the same way as on a computer. Some phone makers' own PDF or gallery apps can also add a signature or image.

In the browser

Microsoft Edge's built-in PDF viewer can draw on a PDF, which is enough for a quick signature with a mouse or pen. Firefox's built-in PDF viewer can add drawings and, in recent versions, images. These are fine for simple forms; for anything important, a dedicated reader gives you more control over size and position.

Sign a Word document

1. Click roughly where the signature should go.
2. Go to Insert > Pictures and choose the PNG from your device.
3. With the picture selected, open Wrap Text (on the Picture Format tab, or the small layout button beside the image) and choose In Front of Text. Now you can drag the signature freely over the signature line instead of it pushing the text around.
4. Resize it by dragging a corner handle, not a side handle, so it does not get squashed.
5. Save a copy as PDF (File > Save As or Export, then choose PDF) before you send it.

Word also has Insert > Signature Line. That creates a box for a certificate-based digital signature, which is a different thing from a picture of your signature and needs a digital ID. For most everyday documents, the picture method is what people mean by "signing in Word".

Sign a Google Doc

1. Choose Insert > Image > Upload from computer and pick your PNG.
2. Click the image and choose In front of text from the small toolbar that appears under it. You can then drag it onto the signature line.
3. Resize from a corner.
4. Use File > Download > PDF document to get a file you can send.

Google Docs also has Insert > Drawing, where you can scribble a signature with the mouse. It works, but the result is usually shakier than a signature drawn on a dedicated canvas, and it is stored only in that document.

What size should the signature be?

A handwritten signature on a printed form is usually about 4 to 6 cm wide (roughly 1.5 to 2.5 inches) and 1 to 2 cm tall. Match that on the page: if the signature is wider than the signature line, it looks pasted on. If it is tiny, it looks like an afterthought. The PNG from the signature maker is exported at screen resolution and trimmed tightly, so shrinking it in the document is fine; avoid making it much larger than the original, or the edges get soft.

Pitfalls to avoid

• White box around the signature: you used a JPG, or a photo with a background. Use a transparent PNG instead.
• Signature jumps when you edit text: in Word and Google Docs the picture is set to sit "in line" with the text. Switch it to in front of text.
• Signature moves or disappears on the other person's computer: you sent an editable file. Send a PDF.
• Pixelated signature: the image was stretched far beyond its original size. Make the signature larger in the signature maker (a wider stroke or a bigger font size) and download it again.
• Form says it needs a "digital signature": that usually means a certificate-based signature or a specific e-signing service, not an image. Read whether electronic signatures are legally binding for the difference.

Frequently asked questions