How to Redact a Document in a PDF and in Word

By Chris Clark, founder of Senior Tech Cafe

Here’s how to redact a document in one sentence: permanently delete the sensitive text rather than covering it, using a real redaction tool like Adobe Acrobat Pro or the one in Mac Preview, then share a fresh copy. A black box drawn on top hides the words from your eyes and nobody else’s.

Ever hit “send” on a document, only to realize it included your Social Security number or Aunt Mabel’s top-secret potato salad recipe? Whoops.

That’s where redaction comes in. Think of it as a digital black marker that actually erases the juicy info you don’t want anyone snooping on.

You don’t need to be a tech genius or shell out big bucks for fancy software, either. This guide covers the safest ways to redact a PDF or a Word file, the common mistakes, and a low-tech option if you’re feeling old-school.

What Is Redaction?

Redacting a document means removing sensitive information from the file itself so it can’t be recovered, then saving a new copy. The removal is the part people skip. Black highlighting in Word, a black box drawn in a PDF editor, or a shape stuck over the text all hide the words, but the words are still in the file.

Think of what you see in spy movies when a “TOP SECRET” document gets declassified: black bars where the names used to be. Except here’s the catch. In the digital world, if you don’t do it right, sneaky people can highlight, copy and paste your “redacted” text into another document and read exactly what you tried to hide.

Proper redaction removes the information completely. It’s like erasing a word from a book, not slapping a sticker over it.

Method 1: How to Redact a PDF With Adobe Acrobat Pro

To redact a PDF with Adobe Acrobat Pro, open the file, choose the Redact a PDF tool, mark the text, and apply. This is the method I use, and it’s the gold standard for PDFs.

Just to be clear, I don’t mean the free Adobe Acrobat Reader. I’m talking about Acrobat Pro, which is very much not free. In the US it’s $19.99 a month on an annual plan, $239.88 if you pay for the year up front, or $29.99 for a single month with no contract. Ouch.

If you only need to redact the occasional document, here’s the trick: Adobe offers a 7-day free trial of Acrobat Pro. Do your redacting, then cancel before the trial ends. Or pay for one month at the no-contract price and cancel. (Cancel an annual plan after 14 days and Adobe charges a fee.)

Here’s how to do it. Tech companies love rearranging things, so if a button has moved, search Adobe’s help site for “redact.”

Open your document in Adobe Acrobat Pro.
Open the redaction tool. Select All tools, then Redact a PDF.
Choose Redact text and images, then drag over the text you want gone. Black boxes appear, but nothing is removed yet. This is just a preview.
Click Apply. Acrobat warns you this can’t be undone. That’s the point. When it asks, choose to remove hidden information too.
Save it under a new name, so you don’t overwrite the original.

And there you go. You’ve officially redacted your document like a digital ninja.

Method 2: Free Online Tools (I Wouldn’t Use Them)

Ah, free tools. They sound great in theory. Who doesn’t love free?

But when it comes to redacting sensitive documents, these tools are about as trustworthy as a shady car salesman. Here’s why:

You’re handing over the original. Most online tools upload your unredacted document to their servers, and you have no idea what they do with it. Selling your data? Keeping a copy? Who knows?
Malware risks. Downloading anything from an unfamiliar website can bring along unwanted baggage, like viruses.
Look-alike sites. It’s hard to tell a real tool from a fake one built to collect documents. Our guide on how to tell if a website is legit helps, but it’s easier to skip them.

If you’re dealing with financial information, medical records or legal documents, steer clear. It’s not worth the risk.

Method 3: The Low-Tech, High-Security Solution

Don’t trust technology? No problem. You can print the document, black it out by hand, and scan it back in. Because the scan is a picture of the page, there’s no hidden text left to copy. Here’s how it works:

Print the document. Grab your trusty printer and print the pages you need.
Redact with a marker. Use a thick black marker and go over each spot a couple of times. Then hold the page up to a window. If you can still read anything, add another coat.
Scan the pages. Use a scanner or your phone’s scanning app to make a new digital copy, and zoom in on screen to check every black bar before you send it.

The downside? It’s slow, and it needs a printer and a scanner (or a phone). For a page or two, though, it’s hard to beat.

Method 4: How to Redact a PDF for Free on a Mac

If you have a Mac, you can redact a PDF for free with Preview, the app that opens PDFs and photos. Its redaction tool removes the text, not just covers it.

Open the PDF in Preview.
Show the Markup toolbar. Click the Show Markup Toolbar button (a pen tip in a circle) at the top of the window.
Choose the redaction tool in that toolbar, then drag across the text you want gone. It turns into black bars.
Save a copy and close it. Apple says the redaction becomes permanent once you close the document, so check your bars before you do.

One catch: if the PDF has a clickable table of contents, entries that point to redacted text aren’t removed. For most letters, statements and forms, that won’t come up.

Windows doesn’t have a free built-in equivalent, which is why the Acrobat trial or the print-and-scan method is the answer on a PC.

How to Redact in Word

To redact in Word, delete the sensitive text and type a row of X’s in its place, then use Word’s Inspect Document feature to strip hidden information before you save a PDF. Word has no built-in redaction tool, and black highlighting doesn’t remove anything: the words stay underneath, and they come along when you save as a PDF.

Here’s the safe way:

Save a copy of the document and work on the copy.
Turn off Track Changes (on the Review tab), so your deletions don’t get saved as a revision someone can undo.
Delete each sensitive item and type a row of X’s (or the word “removed”) where it was.
Inspect the document. Select File, Info, Check for Issues, then Inspect Document. Remove what it finds, especially comments, revisions and hidden text.
Save as a PDF and send that, not the Word file.

Common Pitfalls to Avoid

Even with the right tools, mistakes happen. Here are the redaction blunders to watch for:

Black boxes without redacting: To repeat: drawing a black box over text doesn’t remove it. Always use a real redaction tool, or print and scan.
Leaving hidden information behind: Files carry details you can’t see, like author names, edit history and comments. In Acrobat, say yes when it offers to remove hidden information. In Word, run Inspect Document.
Forgetting the other copies: Your name or account number may appear in a header, a footer or on page 7. Search the document for each item before you call it done.
Sharing the wrong version: Double-check that you’re sending the redacted copy, not the original.

Additional Safety Tips

Before you dive into redacting like a pro, there are a few safety steps you’ll want to keep in mind. Think of these as the “measure twice, cut once” rules for protecting your private info.

They’ll save you from headaches—and potential slip-ups—down the road. Here’s what to do:

Keep a Backup: Before you start redacting, make a backup copy of the original document. You never know when you might need it.
Test the Redaction: After redacting, open the file and try to copy or highlight the blacked-out areas. If you can still access the text, the redaction didn’t work.
Ask for Help: If this all sounds overwhelming, don’t hesitate to ask a tech-savvy friend or family member for assistance.

This Is Worth the Extra Effort

Redacting sensitive information doesn’t have to be complicated or scary.

Whether you use Adobe Acrobat, Preview on a Mac, the careful Word method or the print-and-scan route, the key is to take your time and test the result before you hit send. For more ways to keep your personal information out of the wrong hands, see our online safety guide for seniors.

And remember: when in doubt, there’s always the trusty black marker.

Questions About Redacting Documents

Is Black Highlighting in Word Enough to Redact a Document?

No. Black highlighting only changes the color behind the words, so the text is still there. Anyone can select it, copy it or change the highlight back, and it survives being saved as a PDF. Delete the sensitive words and type a row of X’s in their place, then run Word’s Inspect Document.

Can I Redact a PDF for Free?

Yes, on a Mac. The Preview app that comes with every Mac has a real redaction tool in its Markup toolbar. On a Windows PC there’s no free built-in option, so use Adobe Acrobat Pro’s 7-day free trial for a one-off job, or print the page, black it out and scan it.

How Can I Check That a Redaction Worked?

Open the saved copy, not the original. Try to select the text under each black bar and paste it into a blank document, then search the file for a word you removed. If anything shows up, the text is still there. Redact again with a proper tool and save a fresh copy.

Does the Free Adobe Acrobat Reader Redact PDFs?

No. The redaction tool is part of Adobe Acrobat Pro, the paid version. The free Reader lets you draw boxes and comments on a PDF, but those only cover the text, and anyone can move them or copy what’s underneath. For free, true redaction, use Preview on a Mac.