How to Sign a PDF on Mac Using Preview (Free, No Apps Needed)

I've watched people pay for DocuSign or Adobe Sign when they just needed to sign a lease or a freelance agreement, not realizing their Mac could do the same thing for free. Here's how Preview's signature tool actually works.

Opening the Signature Tool in Preview

1. Open your PDF in Preview (double-click the file, or right-click → Open With → Preview).
2. Click the Markup toolbar button, it's the small pencil icon in the top toolbar, or press ⇧⌘A (Shift + Command + A).
3. The markup toolbar appears. Click the Signature icon, it looks like a cursive "Sign" icon, usually second from the right in the toolbar.
4. A dropdown appears with any saved signatures, plus a Create Signature option at the bottom.

Method A: Sign with Your Trackpad

This is the most common option, and it works well if you sign slowly and deliberately.

1. Click Trackpad at the top of the signature panel.
2. Click Click Here to Begin, then draw your signature on the trackpad using your finger.
3. Press any key when done.
4. Click Done to save the signature.

Tips for a better trackpad signature: use your index finger, sign slowly, and go bigger than you normally would (the signature will be scaled down when inserted). Don't worry about perfection, slight imperfections actually make it look more natural, not less.

Method B: Use Your Webcam (Best Quality)

This option produces the most natural-looking result, it captures your actual pen-on-paper signature.

1. Grab a white piece of paper and sign it in dark ink (blue or black). Make the signature about 3–4 inches wide.
2. In the Preview signature panel, click Camera.
3. Hold the paper up to your webcam, centered in the camera preview. Keep it flat and evenly lit.
4. When Preview detects and highlights your signature in blue, click Done.

If Preview isn't detecting it properly: make sure you have good lighting (not backlit), that the paper is flat, and that the signature is dark enough. Black ink against bright white paper with overhead lighting works best.

Method C: Upload a Signature Image

On newer versions of macOS (Ventura and later), you can also upload an image file as a signature. This is useful if you've already created a clean transparent PNG of your signature using a tool like SignatureHub.

1. In the signature panel, click Image.
2. Click Choose File and select your signature PNG.
3. Click Done.

Placing Your Signature on the Document

Once your signature is created, click on it in the dropdown to insert it into the PDF. It appears as a floating image that you can:

• Drag to position it over the signature field
• Resize by dragging the corner handles (hold Shift to maintain proportions)
• Delete by pressing Backspace if you placed it wrong

When it's positioned correctly, go to File → Save (⌘S) to save the signed PDF. The signature is now embedded in the document.

Managing Saved Signatures

Preview saves your signatures for future use, you'll see them in the dropdown each time you use the signature tool. To delete a saved signature: hover over it in the dropdown and click the X that appears.

You can save multiple signatures, useful if you sign with different versions of your name (formal vs. initials) or if multiple people use the same Mac.

What Preview Can't Do

Preview's signature tool is great for everyday documents, but it doesn't create cryptographically verified digital signatures. If you need a legally binding e-signature with an audit trail, for a real estate transaction, a legal settlement, or anything requiring signature verification, use a dedicated service like DocuSign or Adobe Sign instead.

For most people though, job offer letters, rental agreements, freelance contracts, permission forms, Preview is all you need.