How to Password Protect a PDF in Adobe Reader (Free and Paid Ways)
Published by PDFToolz · Updated · Technical references listed below
You can't password protect a PDF in the free Adobe Acrobat Reader. Reader opens, comments on, fills and signs PDFs, but Adobe lists password protection only in its paid Acrobat plans, such as Acrobat Standard and Acrobat Pro. There, select All tools > Protect a PDF > Protect with password. To do it for free, use PDFToolz Protect PDF, which encrypts the file with AES-256 in your browser, or Adobe's free online tool, which uploads the file to Adobe.
This guide answers whether free Reader can lock a file, then gives the exact steps in Acrobat Standard and Pro, shows how to block printing and copying with Encrypt with Password and explains Acrobat's two password types. If you don't use Adobe software at all, our guide on how to password protect a PDF compares five methods, including Preview on a Mac and Microsoft Word.
Can Adobe Acrobat Reader password protect a PDF?
No. Adobe Acrobat Reader is Adobe's free app for viewing PDFs. Adobe's plan comparison lists 'Password-protect and redact PDFs' under the paid plans, not under Reader. Reader can open a protected PDF when you type its password, but it has no option to add one.
Adobe's free online Password Protect PDF tool is a separate web page, not part of the Reader app. It adds an open password, but your file is handled on Adobe's servers, and Adobe points you to Acrobat Pro to limit printing, editing or copying.
- Free Acrobat Reader: open, read, comment on, fill out and sign PDFs. No password protection.
- Paid Acrobat Standard, Acrobat Pro and Acrobat Studio: add open passwords and permissions passwords.
- Adobe's free online Password Protect PDF tool: adds an open password only. The file is processed on Adobe's servers.
- Free PDFToolz Protect PDF: open password with AES-256 and optional print and copy blocks. The file stays in your browser.
How to password protect a PDF in Acrobat Standard or Pro
In current versions of Acrobat, the quickest route is the Protect with password option. It sets either an open password or a password that limits editing. These steps follow Adobe's help pages for the desktop app. Older versions of Acrobat put the same feature under Tools > Protect > Protect Using Password.
- Open the PDF in Acrobat Standard or Acrobat Pro.
- Select All tools > Protect a PDF, then select Protect with password in the left pane.
- Choose Viewing to require a password to open the file, or Editing to require a password to change it.
- Type the password and type it again. Acrobat asks for at least six characters.
- Select Apply, then save the PDF. Close it and reopen it to check the password prompt appears.
Block printing and copying with Encrypt with Password
Encrypt with Password is Acrobat's advanced option. It lets you set an open password and a permissions password in one dialog, choose which actions stay allowed and pick the encryption level. Adobe's help notes that the Acrobat X And Later compatibility setting encrypts the file with 256-bit AES, the strongest choice in the list.
- Select All tools > Protect a PDF, then select Encrypt with Password under Advanced options.
- Select Require a password to open the document and type the Document Open Password.
- Under Permissions, select Restrict editing and printing of the document and type a Change Permissions Password.
- Pick what is still allowed. Printing Allowed offers None, Low Resolution or High Resolution. Changes Allowed runs from None to options such as inserting, deleting and rotating pages.
- To block copying, clear Enable copying of text, images, and other content.
- Set Compatibility to Acrobat X And Later for 256-bit AES.
- Select OK, confirm each password when asked, then save the file.
Document Open password vs Permissions password in Acrobat
Acrobat's Encrypt with Password dialog asks for two kinds of password, and they protect different things. The Document Open password, which the PDF standard calls the user or open password, encrypts the file so nobody can read it without the password. The Change Permissions Password, which the standard calls the owner password, only tells PDF apps which actions to allow.
Adobe states that all Adobe products enforce permissions, but recipients using third-party apps that don't fully support them may be able to bypass some of the limits. Use the open password for anything confidential. Treat permissions as a polite request.
| Open password | Permissions password | |
|---|---|---|
| Also called | User password, Document Open password | Owner password |
| Needed to open the file | Yes | No |
| Controls | Who can read the file | Printing, copying, editing, commenting |
| Strength | As strong as the password and the encryption | Weak. Ignored by some apps and removable by unlock tools |
| Use it for | Payslips, contracts, medical and bank records | Discouraging casual copying or editing |
Free alternatives to Acrobat Pro
If you only need to lock a file now and then, a paid Acrobat plan is more than you need. Two free options cover the common case of setting an open password. The main difference is where your file goes.
| Option | Cost | Open password | Block printing or copying | Where the file is processed |
|---|---|---|---|---|
| Adobe Acrobat Reader | Free | No | No | Not applicable |
| Acrobat Standard or Pro | Paid subscription | Yes | Yes, with your own permissions password | On your computer |
| Adobe online Password Protect PDF | Free | Yes | No, Adobe points you to Acrobat Pro | Uploaded to Adobe's servers |
| PDFToolz Protect PDF | Free, no account | Yes, AES-256 | Yes | In your browser, never uploaded |
How to password protect a PDF for free with PDFToolz
PDFToolz Protect PDF encrypts the file with AES-256 using qpdf compiled to WebAssembly, running in your browser. The PDF and the password are never uploaded. It works in any modern browser on a computer or phone, with nothing to install.
It sets an open password and can 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. You can't choose your own permissions password, and it can't add permissions without an open password. If you need either, use Acrobat Standard or Pro, or Preview on a Mac.
- 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.
- 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.
- If the PDF already needs a password to open, remove it first with Unlock PDF, then protect it again.
Choose a password that holds up
Guessing an AES-256 key isn't practical, so the password is the weak point. Anyone with a copy of the file can run software that tries password guesses offline, as fast as their hardware allows, and you can't change the password on copies you've already sent. Acrobat also has no way to reset a forgotten open password, so keep an unprotected original somewhere safe.
- Use a long passphrase of four or more unrelated words, not a short word with a number on the end.
- Don't reuse a password from your email, bank or work account.
- Send the password by a different route from the file, such as a text message or a phone call.
- Keep sensitive details out of the file name. Encryption hides the contents, not the name.
Key takeaways
- ✓Free Adobe Acrobat Reader can't add a password to a PDF. Adobe offers it only in paid plans such as Acrobat Standard and Pro.
- ✓In Acrobat, use All tools > Protect a PDF > Protect with password, or Encrypt with Password to set permissions too.
- ✓Choose Acrobat X And Later compatibility in Acrobat for 256-bit AES encryption.
- ✓An open password encrypts the file. A permissions password only asks apps to block printing or copying, and some apps ignore it.
- ✓PDFToolz Protect PDF adds an AES-256 open password for free in your browser without uploading the file.
Tools for the job
Related guides
Frequently asked questions
Can I password protect a PDF in Adobe Reader?
No. The free Adobe Acrobat Reader can open password-protected PDFs but can't add a password. Adobe includes password protection in paid plans such as Acrobat Standard and Acrobat Pro. For free, use Adobe's online tool or PDFToolz Protect PDF.
How do I password protect a PDF without Acrobat Pro?
Use a free tool. PDFToolz Protect PDF encrypts the PDF with AES-256 in your browser and can block printing and copying. Adobe's free online tool adds an open password but uploads the file to Adobe. On a Mac, Preview can add a password with File > Export > Permissions.
Is Adobe's password protect PDF tool free?
Adobe's online Password Protect PDF tool is free and sets a password needed to open the file. Your file is handled on Adobe's servers. For restricting printing, editing or copying, Adobe points you to Acrobat Pro or its free trial, and the desktop Protect tools need a paid Acrobat plan.
How do I stop people printing or copying my PDF in Acrobat?
In Acrobat Standard or Pro, select All tools > Protect a PDF > Encrypt with Password. Under Permissions, select Restrict editing and printing of the document, set Printing Allowed to None, clear Enable copying of text, images, and other content and type a Change Permissions Password. Adobe apps enforce these limits, but some third-party apps ignore them, so add an open password for anything confidential.
What encryption does Adobe Acrobat use to protect a PDF?
With the Acrobat X And Later compatibility setting, Acrobat encrypts the PDF with 256-bit AES. Older compatibility settings use weaker encryption so that very old readers can open the file. PDFToolz Protect PDF always uses AES-256.
Can Adobe recover a forgotten PDF password?
Not an open password. Acrobat has no way to reset a forgotten open password, so keep an unprotected copy of the original or store the password in a password manager. If you own the file and forgot only the permissions password, Adobe suggests printing it to Adobe PDF to make a new, unrestricted copy.
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
- Adobe Acrobat vs. free PDF tools from Adobe
- Password protect PDF from Adobe Acrobat online
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