How to Password Protect a PDF File: 5 Ways, Free and Paid
Published by PDFToolz · Updated · Technical references listed below
To password protect a PDF, open it in a tool that can encrypt PDFs, set an open password and save a new copy. Anyone who opens that copy must type the password first. PDFToolz Protect PDF in any browser and Preview on a Mac do it for free, and Word for Windows can add a password when it saves a document as a PDF. In Adobe software, it needs a paid Acrobat plan or Adobe's free online tool.
This guide compares five methods side by side, gives the steps for each and explains the difference between an open password and a permissions password. It also shows why permissions are easy to get around and how to pick a password that protects the file. For what the free Adobe Reader can and can't do, see our guide to password protecting a PDF in Adobe Reader.
Ways to password protect a PDF compared
Every method below sets an open password, which is the part that keeps people out. They differ in cost, in whether you can also limit printing and copying, and in whether your file leaves your device.
| Method | Cost | Open password | Limit printing or copying | File leaves your device |
|---|---|---|---|---|
| PDFToolz Protect PDF | Free | Yes, AES-256 | Yes | No, runs in your browser |
| Adobe Acrobat Standard or Pro | Paid | Yes | Yes | No, desktop app |
| Adobe online Password Protect PDF | Free | Yes | No, Adobe points you to Acrobat Pro | Yes, handled on Adobe's servers |
| Preview on Mac | Free, built in | Yes | Yes | No |
| Microsoft Word for Windows (Save as PDF) | Included with Word | Yes | No | No |
Password protect a PDF in your browser with PDFToolz
PDFToolz Protect PDF works on any computer or phone with a modern browser, with no account or install. It encrypts the PDF with AES-256 using qpdf compiled to WebAssembly, so the file and the password never leave your device.
It sets an open password and can also block printing, copying or both. When you block an action, the tool sets a random permissions password that nobody is told, so the open password alone can't lift the limits in a PDF reader. It can't set a permissions password you choose, or permissions without an open password.
- Open Protect PDF and select your PDF. It protects one file at a time.
- Type a password under Set a password. It is used exactly as typed, spaces included, and there is no confirm box, so type carefully.
- To limit the file, turn on Block printing, Block copying or both under Permissions (optional).
- Press Protect PDF, then Download PDF. The new file ends in -locked.pdf and your original is unchanged.
- Open the new file once to check the password works before you send it.
Password protect a PDF in Adobe Acrobat
Adding a password needs a paid Acrobat plan, such as Acrobat Standard or Acrobat Pro. The free Acrobat Reader can open protected PDFs but can't add a password. These steps follow Adobe's help pages for the current desktop app. Our Adobe Reader guide covers each Acrobat option in more detail.
To also limit printing, editing and copying, use Encrypt with Password under Advanced options in the same Protect a PDF tool. It lets you set both passwords, choose Printing Allowed and Changes Allowed levels and pick a compatibility level. Acrobat X And Later uses 256-bit AES.
Adobe also has a free online Password Protect PDF tool. You type the password, retype it and select Set password. It only sets an open password, and the file is handled on Adobe's servers.
- Open the PDF in Acrobat Standard or Pro.
- Select All tools > Protect a PDF > Protect with password.
- Choose Viewing to require a password to open the PDF, or Editing to require one to change it.
- Type the password twice. Acrobat requires at least six characters.
- Select Apply, then save the file.
Password protect a PDF on a Mac with Preview
Preview, the PDF viewer built into macOS, can add an open password and an owner password that controls printing and changes. These steps follow Apple's Preview User Guide.
- Open the PDF in Preview and choose File > Export.
- To keep the original unprotected, type a new name for the copy.
- Click Permissions, select Require Password To Open Document, then type the password and retype it.
- To limit actions, leave an action's checkbox unselected so it needs the owner password, then type an owner password in the Owner Password section and retype it.
- Click Apply, then click Save. The changes take effect the next time the PDF is opened.
Password protect a PDF from Microsoft Word
If the PDF starts as a Word document, Word for Windows can encrypt it as it saves. This option only sets an open password. It can't limit printing or copying. Microsoft describes it only for the Windows desktop app, not Word for Mac or Word for the web. On a Mac, save the PDF from Word and then protect it in Preview.
- In Word, select File > Save a Copy, or File > Save As for an unsaved file, then select Browse.
- Set the file type to PDF.
- Select Options and turn on Encrypt the document with a password, then select OK.
- In the Encrypt PDF Document box, type the password, retype it and select OK.
- Select Save.
Open passwords vs permissions passwords
A PDF can have two passwords. The open password, also called the user password, encrypts the file. Without it, nobody can read the pages. The permissions password, also called the owner password, lets the file open freely but tells PDF apps to block actions such as printing, copying text or editing.
For anything private, such as payslips, contracts, ID scans or medical records, the open password is the one that matters. Permissions are useful for discouraging casual copying of a file you're happy for people to read.
| Open (user) password | Permissions (owner) password | |
|---|---|---|
| Needed to open the file | Yes | No |
| Keeps the content private | Yes | No |
| Blocks printing, copying or editing | No, anyone who opens it has full access unless permissions are also set | Yes, in apps that respect it |
| Removable without the password | No | Yes, by many unlock tools |
Why permissions passwords are weak
A PDF with only a permissions password opens without any password, which means any app can read its content. The limits are flags that the app is asked to respect. Adobe states that its own products enforce them, but recipients using third-party apps that don't fully support them may be able to bypass some of the restrictions.
Removing them is routine. PDFToolz Unlock PDF lifts print, copy and edit limits with no password at all, and Adobe's own help suggests printing to Adobe PDF if you forget the permissions password on a file you own. Anyone can also take a screenshot. Use permissions to set expectations, and use an open password to protect secrets.
Key takeaways
- ✓To password protect a PDF, set an open password in a tool that encrypts PDFs, then save and test a new copy.
- ✓PDFToolz Protect PDF in any browser and Preview on a Mac are free. Word for Windows can add an open password when it saves as PDF.
- ✓Adobe Acrobat needs a paid plan to add a password. Its free online tool sets an open password but uploads the file.
- ✓Permissions passwords only ask apps to block printing or copying and are easy to remove. The open password is what protects the content.
- ✓Use AES-256 and a long, unique passphrase, and send the password separately from the file.
Tools for the job
Related guides
Frequently asked questions
How do I protect a PDF file with a password for free?
Open PDFToolz Protect PDF, select the file, type a password and press Protect PDF, then download the -locked.pdf copy. It uses AES-256 and runs in your browser, so the file isn't uploaded. On a Mac, Preview can also do it with File > Export > Permissions.
What is the difference between an open password and a permissions password?
An open password, also called the user password, encrypts the PDF, so nobody can see the pages without it. A permissions password, also called the owner password, lets anyone open the file and only asks PDF apps to block printing, copying or editing. Many unlock tools remove permissions without the password, so use an open password for private files.
Can I password protect a PDF on a Mac without Adobe?
Yes. Open the PDF in Preview, choose File > Export, click Permissions, select Require Password To Open Document and type the password twice. Click Apply, then Save. You can also set an owner password to limit printing and changes.
Can I password protect a PDF in Word?
Yes, when you create the PDF from a Word document in Word for Windows. Save a copy as PDF, select Options, turn on Encrypt the document with a password and type the password twice. This sets an open password only. To protect an existing PDF, use a PDF tool instead.
Can I password protect a PDF on my phone?
Yes. PDFToolz Protect PDF runs in the browser on iPhone and Android, so you can select the PDF from your files, set a password and download the protected copy without installing an app or uploading the file.
Can a password-protected PDF be cracked?
A permissions password can be removed easily, often with no password at all. An open password with AES-256 can only be attacked by guessing the password, so a long, unique passphrase would take impractically long to guess, while a short or common one can fall quickly.
Related terms
Sources and further reading
- Add passwords to PDFs in Acrobat from Adobe Acrobat Help
- Restrict PDF printing, editing, and copying in Acrobat from Adobe Acrobat Help
- Regain access to locked PDFs in Acrobat from Adobe Acrobat Help
- Password-protect a PDF in Preview on Mac from Apple Support
- Save or convert to PDF or XPS in Office desktop apps from Microsoft Support
- Password protect PDF from Adobe Acrobat online
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