How strong is the protection?

The document is encrypted with 256-bit AES, which is what the PDF standard specifies for new documents and what Acrobat itself uses. Without the password the contents cannot be read. The strength in practice is the strength of your password: a long one that is not a dictionary word is what keeps a determined person out.

What if I forget the password?

Then the document cannot be opened, by anyone. We do not keep the password — it is removed from our records the moment the job finishes — and we cannot break the encryption. Type it carefully, use the eye icon to check it, and keep a copy of it or of the unprotected original somewhere safe.

What do the print and copy settings actually do?

They set the document's permissions, which PDF readers honour: with ‘Print only’, Acrobat and Preview grey out copy and edit; with ‘Read only’ they grey out print as well. Be clear about what this is, though — the PDF format cannot enforce these restrictions the way it enforces the password, and anyone who can open the document can lift them with a tool such as Unlock PDF. Use them to signal intent, not to prevent a determined person.

Will the PDF still work everywhere?

Yes. AES-256 is supported by every mainstream reader made in the last fifteen years: Adobe Reader, macOS Preview, every major browser's built-in viewer and the readers on iPhone and Android. Only very old software may fail to open it.

Does protecting change the document?

No. Encryption wraps the file's contents; it does not re-render or alter them. Every page keeps its size, text stays selectable once the document is open, and images keep their resolution. The file comes back close to its original size.

Can I protect a PDF that already has a password?

Not directly — it is refused rather than double-locked, because we never guess at a password we do not have. Run it through Unlock PDF with its current password first, then protect the result with the new one.

Is this converter free?

Yes. Every conversion on ConvertNicely is free to use, with no account, no watermark on the result and no limit on how many files you convert.

What happens to my files?

Your uploaded file is deleted from our servers the moment the conversion finishes, whether it succeeded or failed. The converted result is deleted automatically one hour later, and you can delete it yourself at any time with the Delete button.

Is there a file size limit?

Files up to 95 MB are accepted for this conversion. Larger limits apply to paid plans in future, but the free limit is generous enough for the overwhelming majority of PDF conversions.

Do I need to install anything?

No. ConvertNicely runs entirely in your browser and on our servers, so there is nothing to download or install. It works the same on Windows, macOS, Linux, Android and iOS.

Does it work on a phone?

Yes. The whole site is built mobile-first, so you can upload from your camera roll or files app, convert, and download the result without leaving your browser.

Free

Protect a PDF with a Password

Type a password, type it again, and download a copy of your PDF that asks for it before it opens. The document is encrypted with AES-256, the strongest the PDF format offers and one every current reader — Acrobat, Preview, Chrome, Edge, Firefox, phones — understands. Nothing about the pages changes: the text stays selectable, the images keep their quality, and the file is much the same size.

Also known as: password protect PDF · encrypt PDF · lock PDF

Files up to 95 MBTypically under a minute

Drop your file hereor choose a file from your devicePDF · up to 95 MB

Encrypted upload · deleted right after conversion

Your files are deleted automatically

Uploads are removed as soon as processing finishes, and converted files are deleted after 1 hour. Read our privacy policy.

How to protect a PDF with a password

Step 1
1. Add your PDF file
Drag your PDF file into the box, or choose it from your device. It can be up to 95 MB.
Step 2
2. Choose your settings
Fill in “Password to open the PDF”, then type it again to confirm. Adjust “Once it is open, others can” (Print, copy and edit), or keep the starting values in brackets, which suit most files.
Step 3
3. Press Protect PDF
The work happens on our servers, and you can follow its progress.
Step 4
4. Download your PDF file
Your upload is already deleted, and the result is deleted after one hour.

Worth knowing

There is no way to recover a forgotten password — not for you, and not for us — so keep it somewhere safe. The password is the real protection. PDF readers honour the print and copy restrictions, but the format cannot enforce them, and anyone with the password can remove them with Unlock PDF. A PDF that already has a password is refused: unlock it first, then protect it with the new one.

Why protect a PDF with a password?

Emailing a contract, payslip or medical report that only the recipient should be able to open
Sending an invoice or statement that contains bank details
Sharing a draft that must not be printed or copied by everyone who sees it
Keeping a scanned passport or ID document safe on a shared drive

What changes

What protect a PDF with a password changes, and what it leaves alone
Property	Before	After
Opening	Anyone	Password required
Encryption	None	AES-256
Pages and text	Original	Unchanged
Printing and copying	Allowed	As you choose

Frequently asked questions

Page updated 3 October 2026

All PDF converters

Protect a PDF with a Password

How to protect a PDF with a password

1. Add your PDF file

2. Choose your settings

3. Press Protect PDF

4. Download your PDF file

Why protect a PDF with a password?

What changes

Frequently asked questions

Unlock PDF

Watermark PDF

Compress PDF

Merge PDF

Protect a PDF with a Password

How to protect a PDF with a password

1. Add your PDF file

2. Choose your settings

3. Press Protect PDF

4. Download your PDF file

Why protect a PDF with a password?

What changes

Frequently asked questions

How strong is the protection?

What if I forget the password?

What do the print and copy settings actually do?

Will the PDF still work everywhere?

Does protecting change the document?

Can I protect a PDF that already has a password?

Is this converter free?

What happens to my files?

Is there a file size limit?

Do I need to install anything?

Does it work on a phone?

Related conversions

Unlock PDF

Watermark PDF

Compress PDF

Merge PDF