How to Password Protect a PDF on Mac with Preview

Steps use macOS 14 and later names. Menu wording can differ slightly between versions.

Choose the protection you need

• Keep the file private. Require a password to open it. Anyone without the password sees nothing.
• Let people read it but limit what they do. Apple says you can use a password to control access to printing, copying text and adding annotations. Leave those actions unselected so they need the owner password.
• Both. Set an open password and an owner password. The two can be the same or different.

Two passwords, two jobs

Apple says the owner password can match the open password or differ from it. Use different passwords if you will give the open password to readers but keep the owner password to yourself.

Set a password in Preview

1. Open the PDF

   Open Preview, then open the PDF you want to protect.

2. Start an export

   Choose File > Export. Enter a new file name. Apple says this creates a protected copy and leaves the original unprotected.

3. Click Permissions

   Click the Permissions button.

4. Require a password to open

   Select Require Password To Open Document. Enter the password and retype it to verify.

5. Choose what is allowed

   Optional. Select the checkbox next to an action to allow it without the owner password. Leave a checkbox unselected to require the owner password for that action.

6. Set the owner password

   In the Owner Password section, enter a password and retype it.

7. Apply and save

   Click Apply, then click Save.

8. Test the copy

   Close the file and open the new copy. Preview should ask for the password. Then try the viewers your reader will use.

Change permissions later

Apple says Edit Permissions is for a PDF where you have already set an owner password.

1. Open the protected PDF in Preview.
2. Choose File > Edit Permissions.
3. Select Require Password To Open Document and enter a password, or change which features need a password, or enter a new owner password.
4. Click Apply.

Apple says these changes also take effect the next time the PDF is opened.

How to test what you set

• Open the new copy from Finder. It should ask for the password before it shows any page.
• If you restricted printing or copying, test in the viewers your recipient will use. Apple's page describes the setting but does not say how other apps treat it.
• Check the file name and the message you send it in. Neither is protected.
• Send the password by a different route than the PDF. A password in the same email as the file defeats the point.

For identity documents, the ID and passport scans scenario lists where stray copies of a scan tend to hide, beyond the PDF itself.

What a PDF password does not do

• It protects one file. Copies you made before protecting it stay as they are.
• It does not protect your folder. For many files, use an encrypted disk image: see encrypted disk images on Mac.
• Apple's page does not describe how to recover a forgotten PDF password. Keep it in a password manager.
• Old backups may still hold the unprotected original. See how to encrypt a Time Machine backup.
• Apple's page says a password can be required to open a PDF. It does not describe the cipher, so this guide gives no strength figure.

Other documents on your Mac

Pages, Numbers and Keynote use File > Set Password. Apple says it encrypts the file. Notes can lock a note. Both are covered in password protect a folder on Mac without Disk Utility. For whole folders, see how to password protect a folder on Mac.