The fastest way to sign a PDF depends on what you already have

You can add your signature to a PDF in three main ways: draw it directly into the document using free software, insert an image of your handwritten signature, or use your trackpad or mouse to write one. The method you choose depends on whether you have a scanner, whether you need the signature to look handwritten, and what software you already have on your computer.

Most people use either Adobe Reader (free) or Preview on Mac (built in), both of which let you sign without buying anything. If you need a more formal digital signature that proves who signed the document, that is a different process — but for most everyday PDFs, a drawn or image-based signature works fine.

Key Takeaways

  • Adobe Reader's free version lets you add a signature by drawing it with your mouse, trackpad, or stylus directly into any PDF.
  • If you have a scanned image of your signature, you can insert it into a PDF using Preview on Mac or Adobe Reader on any computer.
  • Preview on Mac has a built-in signature tool that captures your signature from your trackpad without needing any other software.
  • After you sign, save the PDF with a new filename so you do not overwrite the original unsigned version.

Adding a signature in Adobe Reader (Windows and Mac)

Adobe Reader is free and works on both Windows and Mac. Open the PDF you want to sign, then look for the "Fill & Sign" button in the right panel. Click it, then click "Sign" in the toolbar that appears. You will see options to draw your signature with your mouse or trackpad, type your initials, or upload an image of your signature.

To draw your signature, click the pencil icon and use your mouse or trackpad to write your name in the box that appears. If your trackpad is too difficult to write on, you can type your name instead and choose a signature font. Once you are happy with how it looks, click "Apply" and then click on the PDF where you want the signature to appear. You can resize it by dragging the corners.

When you are finished, go to File and choose "Save a Copy" or "Save As". This creates a new file with your signature in it and leaves the original unsigned PDF untouched. Give it a clear name like "Contract_Signed_YourName.pdf" so you know which version has your signature.

Using Preview on Mac to add a signature

If you use a Mac, Preview is already installed and has a built-in signature tool. Open your PDF in Preview, then click the Markup toolbar button (it looks like a toolbox). Click "Signature" in the toolbar, and Preview will ask you to sign on your trackpad. Write your signature as naturally as you can — Preview captures it and saves it for future use.

Once your signature is captured, you can click anywhere on the PDF to place it. Resize it by dragging the corners until it looks right. If you do not like how it turned out, you can delete it and create a new signature. Preview lets you store multiple signatures, so you can have different versions for different documents.

Save your signed PDF by pressing Command+S or going to File and clicking "Save". If the original PDF is read-only, Preview will ask you to save it with a new name. Use a filename that makes it clear the document is signed.

Inserting a scanned image of your signature

If you have a handwritten signature that you have already scanned or photographed, you can insert that image into your PDF instead of drawing one. This works in Adobe Reader, Preview, or most PDF editors. The image should be a clean scan with your signature on a white background and as little extra space as possible.

In Adobe Reader, use the "Fill & Sign" tool and click the image icon when you are in signature mode. Choose your signature file from your computer. In Preview on Mac, go to Tools, then Markup, then click the image icon and select your signature file. Position and resize it on the page, then save.

Before you scan your signature, sign a blank piece of paper with a pen you normally use. Scan it at 300 dots per inch (DPI) or higher so it stays clear. Save it as a PNG or JPG file in a folder you can find easily — you will use this same image file for every document you sign, so keep it somewhere you remember.

What to do if you cannot draw with your mouse or trackpad

Drawing a signature with a mouse is difficult for most people, and a trackpad is even harder. If you do not have a stylus or tablet, your best options are to type your name in a signature font or use a scanned image of your actual signature.

Typing your name works fine for many documents, especially internal ones or informal agreements. Adobe Reader and Preview both offer signature fonts that look handwritten. Choose one you like, type your name, and place it on the page. It is not as personal as a handwritten signature, but it is faster and clearer.

If you need something that looks more like your real signature, spend five minutes scanning or photographing your actual signature on paper. This takes longer the first time, but you can reuse that image on every PDF you sign from then on, which saves time overall.

Placing your signature in the right spot on the PDF

Most PDFs have a blank line or box where you should place your signature. Look for lines labeled "Signature," "Sign here," or an empty box. Click or drag your signature to that spot and resize it so it fits neatly without covering any text.

If the PDF does not have a marked signature area, place your signature in the bottom right corner of the page or near your printed name if one appears on the document. Make sure it does not cover any important text or make the document harder to read. If you are signing a contract or legal document, check if there are instructions about where the signature should go.

You can place multiple signatures on the same PDF if it needs to be signed by more than one person. Just add each signature in the correct location. If someone else needs to sign after you, save your version and send it to them — they can open it and add their signature using the same steps.

Saving your signed PDF so you do not lose the original

Always save your signed PDF with a new filename. This keeps the original unsigned version safe in case you need it again. In Adobe Reader, use "Save a Copy" or "Save As" instead of regular "Save." In Preview, use "Save As" from the File menu.

A good naming system helps you find signed documents later. Use something like "LeaseAgreement_Signed_March2024.pdf" or "TaxForm_YourName_Signed.pdf". Include the date if you sign multiple versions of the same document. Store signed PDFs in a folder you check regularly, not scattered across your Downloads folder.

If you are sending the signed PDF to someone else, include a note about what it is. A quick email saying "Here is the signed contract" is clearer than just attaching a file. If the other person needs to sign it too, let them know they should save their version with a different name so both signatures are preserved.

Frequently Asked Questions

Can I sign a PDF on my phone or tablet?

Yes. Adobe Reader and Preview both have mobile versions that let you sign PDFs. On an iPad or Android tablet, you can use your finger or stylus to draw a signature directly on the screen, which is much easier than using a mouse. On a phone, the screen is smaller, but you can still add a signature using the same tools.

What if the PDF is locked or says I cannot edit it?

Some PDFs are set to read-only, which means you cannot add signatures or make changes. Try opening it in a different program — Adobe Reader sometimes can sign read-only PDFs even though other programs cannot. If that does not work, the person who created the PDF may need to unlock it first and send you an editable version.

Is a signature I draw in Adobe Reader legally valid?

A drawn or typed signature in Adobe Reader is not a legally binding digital signature in the formal sense. For most everyday documents, it is fine. If you need a signature that proves who signed the document and when, you need a certified digital signature, which is a different process that requires a certificate from a trusted authority.

Can I reuse the same signature on multiple PDFs?

Yes. Once you create a signature in Adobe Reader or Preview, both programs save it so you can use it again on future documents. You do not have to redraw or re-scan it each time. Just open a new PDF, go to the signature tool, and your saved signature will be available to place on the page.

What happens if I make a mistake while signing?

You can delete the signature and try again. In Adobe Reader, right-click the signature and choose "Delete." In Preview, click the signature and press Delete. Then use the signature tool again to add a new one. You can redo this as many times as you need before you save the file.