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How to password-protect a PDF file in less than 30 seconds
You can keep your personal documents secure on a Windows PC or Mac by using this simple tech tip from our experts
The widely used PDF format supports data-saving encryption, allowing you to protect sensitive documents so that only those with the correct password can access them.
In the old days, you’d need a dedicated application called a PDF reader to view PDF files – most people needed to install Adobe’s free Acrobat Reader (now called Adobe Reader) on their computers to open PDFs. Now, however, because PDF is an open standard, many devices and apps have built-in support for the format.
Below, we explain in simple terms how you can easily lock up your files with a secure password. Plus, discover how to annotate a PDF in case you need to email comments or suggestions.
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Each month, we feature one of the most popular questions answered by our Tech Support team.
Question of the month: how do I secure a PDF file?
'I've created a PDF document with personal information I need to send to my family. How can I add a password to this file so nobody else can access it?'
Which? Tech Support member
Add a password to a PDF
On Windows
You can use the free PDFGear app to encrypt a PDF.
Open the PDF file in the program and click the Tools tab at the top of the window. Now, click the Password icon, enter and, in the Set Password box, confirm your chosen Password, then click OK.
Once you're done, click the Save icon in the top left (it looks like an old-fashioned floppy disk).
On Mac
Right-click any PDF file and choose Open With > Preview, then wait for your document to load.
In the window that opens, head to File > Export and choose Permissions. Tick the box at the top of the menu that says Require Password To Open Document.
Fill in the user password and verify it, then do the same for the Owner Password. The user password is required to open the PDF, while the owner password controls permissions for what actions can be performed on the PDF.
When you're ready, choose Apply.
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Do more with PDF files
- Create your own PDFs The easiest way to do this is to use a word-processing app to design your document, adding text, images, formatting and so on, as needed. When you’re finished, you can then export your document as a PDF file. Most word processors nowadays allow you to do this. In Microsoft Word, for example, click File > Save as, then select PDF from the File format dropdown menu.
- Edit an existing PDF If you use Microsoft Word, you can click File > Open, then browse for your PDF file and open it. Word will automatically convert the PDF to a fully editable document, which you can change as much as you like before re-saving it as a PDF or as a Word document, if you prefer. If you don't have Word, you could use the free office suite LibreOffice in a similar way. Click File > Open and browse for your PDF file.
- Annotate a PDF When you open a PDF in Edge on a Windows PC, you'll see a toolbar of simple annotation tools along the top of the browser window. Click the highlighter pen icon and you'll be able to highlight sections of text in your document. You can also draw shapes, overlay text and erase any annotations you don't want. On a Mac, open a PDF in Preview, then click the icon of a pen nib in a circle to reveal the annotation tools.
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