How to password-protect a PDF
A password on a PDF means only people who know it can open the file, even if the email is forwarded or the laptop is lost. Macs can do it with Preview, and Windows users with Microsoft Word can do it when they save a document as a PDF. Here are both, how to get the password to the reader safely, and how this fits with sending documents for signature.
Updated November 5, 2026 · 3 min read
On a Mac, with Preview
- 1
Open the PDF in Preview
Double-click the PDF, or right-click it and choose Open With › Preview.
- 2
Export a copy
Choose File › Export. Give the file a new name if you want to keep an unprotected original.
- 3
Set the password to open
Click Permissions, select Require Password To Open Document, then type the password and type it again to confirm.
- 4
Set the owner password
Preview also asks for an owner password, which controls printing, copying and changes. It can be the same as the first password or a different one. Tick any actions readers may do without it.
- 5
Apply and save
Click Apply, then Save. The next time the file is opened, it asks for the password. To change it later, open the file and choose File › Edit Permissions.
On Windows, with Word
Windows has no built-in tool that adds a password to an existing PDF, but Word can encrypt a PDF as it creates one. Open the document in Word, choose File › Save a Copy, pick PDF as the type, then select More options and Options. Tick Encrypt the document with a password, click OK, type the password twice and save. If you start from an existing PDF rather than a Word file, Adobe Acrobat and other PDF editors have a password option, usually under a Protect menu.
Send the password another way
A password in the same email as the file protects nothing. Text it, say it on the phone, or agree on one in advance. And store it somewhere safe: if you forget a PDF's open password, there's no reset button.
Passwords and e-signatures
If the document is going out for a signature, a password on the file gets in the way. SignMaster needs to read the pages to place fields, so a password-protected PDF is turned away at upload with a message to that effect. Remove the password first: in Preview, open the file, choose File › Edit Permissions, clear the password options and save a copy.
To protect the signing itself, put the lock on the link instead. In Message & settings, under Private notes & access codes, choose Code you share, a code you give the signer by phone or text, or Emailed code, a one-time code sent to their inbox. The document won't open until they enter it. SignMaster doesn't add a password to the signed PDF that's emailed afterwards; if your policy requires one, export a protected copy with the steps above before you forward it.
Questions? Answers.
How do I password-protect a PDF for free?
On a Mac, use Preview: File › Export, Permissions, then Require Password To Open Document. On Windows, Word can encrypt a PDF as it saves one, with no extra software.
What's the difference between an open password and an owner password?
An open password stops anyone without it from viewing the file. An owner password lets people view it but limits printing, copying and editing unless they have the password.
Can I send a password-protected PDF for e-signature?
Not to SignMaster; it refuses protected files because it can't read the pages. Remove the password, upload the PDF, and use an access code on the signing link instead.
Is a password-protected PDF secure?
With a strong, unique password and modern encryption, it's a solid lock for a file at rest. A short or reused password is easy to guess, and the protection ends once someone opens the file and saves an unprotected copy.
Sources
- Apple, Password-protect a PDF in Preview on Mac · support.apple.com
- Microsoft, Save or convert to PDF in Office desktop apps · support.microsoft.com