Guide · Updated · By Buğra Sözeri
How to Sign a PDF on Mac
Preview, the app that opens PDFs by default on macOS, has a built-in signature tool. You create your signature once and can reuse it on any document.
Step by step
- Open the PDF in Preview. Double-click the PDF. If another app opens it, right-click the file and choose Open With, then Preview.
- Show the Markup toolbar. Click the Show Markup Toolbar button (the pen tip icon) in the toolbar if the Markup toolbar is not already showing.
- Click Sign. Click the Sign button in the Markup toolbar. If you have no saved signature, Preview asks you to create one.
- Create your signature. Choose Trackpad and sign with your finger, Camera and hold a signature written on white paper up to the camera, or Select Device to sign on a nearby iPhone or iPad. Click Done.
- Place the signature. Click Sign again and click the signature you want to add. Drag it into position and resize it with the corner handles.
- Save the file. Choose File > Save, or File > Export as PDF to keep the original untouched.
Adding the date or your name
Use the Text tool in the Markup toolbar to add a text box for the date or your printed name. Preview also detects form fields in many PDFs, so you can click a field and type directly.
A browser-based option
If you would rather not install anything, eSignSimple's free Sign PDF tool is included with a free account (sign up with Google) and runs in your browser. You upload the PDF (it is encrypted at rest), draw or type a signature, add the date, and download the signed copy with an audit trail; it counts as one of your monthly documents.
Troubleshooting Preview signatures
If the Sign button is greyed out, the PDF may be locked by its author; check File > Get Info or the Inspector for security settings, and ask the sender for an unlocked copy. If your signature appears but disappears in the recipient's app, export a new copy with File > Export as PDF, which tends to flatten annotations more reliably than a plain save.
If the camera method gives a grey or patchy result, sign with a thick black pen on bright white paper and hold it steady against a light background.
Preview vs. sending for signature
Preview signs your copy. Sending for signature is for when you need a client, landlord or employee to sign: the service emails them a link, reminds them, and produces a certificate of completion with an audit trail. If you already use Preview for your own signature, the rest of the workflow is covered in how to get a contract signed remotely.
Windows users can follow the equivalent steps in how to sign a PDF on Windows, and anyone who wants to avoid the printer entirely should read how to sign a PDF without printing.
How do I sign a PDF on Mac when there are form fields too?
Many PDFs you get from banks, schools and government offices are fillable forms. Preview recognises most of them: click a field and type, tick checkboxes with a click, and move from field to field with the Tab key. Fill every field before you add the signature, because some forms recalculate or reflow when fields change, and you do not want to move the signature twice.
Flat PDFs, typically scans, have no real fields. Use the Text tool in the Markup toolbar to add text boxes, then set the font size in the Text Style menu so your entries match the printed form. For long forms, our guide on how to fill out a PDF has a sensible order of work. When everything is complete, sign last, then export a fresh copy.
Why does my Preview signature look different on another computer?
On your Mac the signature is crisp; on the recipient's Windows PC it looks bold, faint, or slightly out of place. That happens because the signature is stored as an annotation, and other viewers draw annotations in their own way. Usually it is cosmetic, but occasionally a viewer drops the annotation entirely.
The cure is the same as for any PDF: export a flattened copy. Choose File > Export as PDF, or File > Print and then PDF > Save as PDF from the print dialog. The printed version embeds the signature into the page itself. Check it in a browser or another PDF app before you send it. Keep the editable Preview copy in case you need to fix a typo, and send only the flattened one.
Using your iPhone or iPad to create a cleaner Mac signature
Preview's device option is the best-kept secret of Mac signing. When you create a new signature, choose the iPhone or iPad option; as long as both devices use the same Apple Account and are nearby with Wi-Fi and Bluetooth on, a drawing pad opens on the phone. Draw with your finger or Apple Pencil, tap Done, and the signature appears in Preview on the Mac, ready to place.
If nothing appears on the phone, unlock it and keep it close to the Mac, check both are signed in to the same Apple Account, and try again. The camera method is the fallback: sign on white paper with a thick black pen, hold it up to the Mac's camera so the signature sits on the blue line, and wait for Preview to capture it.
When is Preview not enough on a Mac?
Preview is the right tool when you sign your own copy. It is the wrong tool in three situations: when you need a client or tenant to sign, when several people must sign in a set order, and when you will need to prove who signed and when. In each case a signing service fills the gap, and on a Mac it runs in Safari or Chrome with nothing to install.
A small consultancy, for example, might sign supplier forms in Preview every week but send its own service agreement through a signing link, so the client signs from a phone and the certificate lands in both inboxes. The service agreement template is a good starting point for that second case.
Our take
Preview is genuinely excellent and most Mac users do not need anything else for their own signature. Our one piece of advice: capture your signature with an iPhone or iPad rather than the trackpad. Trackpad signatures tend to look like a child's drawing, and a clean signature makes the document look like something you took seriously. What Preview cannot do is collect anyone else's signature with proof, so do not let a good tool for one job convince you it covers the other.
Sources and further reading
Frequently asked questions
Is signing a PDF in Preview free?
Yes. Preview comes with macOS and the signature feature costs nothing.
Where are Preview signatures stored?
Signatures are saved on your Mac and can sync to other Apple devices signed in to the same Apple Account, depending on your settings.
Can I remove a saved signature?
Yes. Click Sign and remove the signature from the list of saved signatures.
How do I get someone else to sign?
Send them the PDF, or use an e-signature service to track signing with an audit trail. eSignSimple does this on every plan, including Free (3 documents a month), and signers do not need an account.
Can I sign a Word document in Preview?
Preview can open some Word files but is not built to sign them. Export the document to PDF from Word or Pages first, or upload the Word file to an e-signature service that converts it for you.
Does Preview add a date automatically?
No. Add the date with the Text tool in the Markup toolbar.
Can I sign a PDF on Mac without Preview?
Yes. Adobe Acrobat Reader for Mac has Fill & Sign, and browser tools such as eSignSimple's Sign PDF tool work in Safari, Chrome or Firefox. Preview is simply the quickest because it is already installed.
How do I sign a PDF on Mac and keep the original?
Duplicate the file first (File > Duplicate) or use File > Export as PDF after signing, which creates a new file and leaves the original as it was.
Why does Preview say the document is locked?
Either the file is locked in Finder or its author restricted editing. Unlock it in File > Get Info if it is your own file; if the restriction comes from the author, ask for an editable copy or a signing link rather than trying to remove it.
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