How to Black Out Text in PDF: 4 Ways (Windows, Mac & Online)

To black out text so it can't be recovered, use true redaction — not a black box. A black rectangle only hides text visually; anyone can select, copy, or delete the box to reveal what's underneath. True redaction deletes the underlying data from the file itself. Below are four ways to black out text — and a clear warning about which ones actually remove the data versus which only cover it.

Before you pick a method, one distinction decides everything: are you covering the text or deleting it? Get that wrong and a "blacked-out" bank number can leak the moment someone opens the file in another editor.

Part 1. Black Box vs. True Redaction: Pick the Right One First

Most "black out text" guides quietly skip the difference between hiding and removing. That gap is exactly where sensitive PDFs leak. Match your situation to the right method before you start:

If the data must be truly gone, only the redaction rows count. A black box is fine for a mockup and dangerous for a payslip.

Part 2. Method 1 — Black Out Text with UPDF (True Redaction, Windows & Mac)

UPDF redacts text on your device rather than uploading it to a server, which matters when the file is a contract or bank statement. Its Search & Redact function also finds every instance of a name or number across a long document, so you don't miss a stray copy on page 40. Here's how to black out text in a PDF with true redaction:

Step 1. Open a copy of your PDF in UPDF (keep the original somewhere safe). If you don't have UPDF yet, download UPDF for free and install it in under a minute.

Step 2. Click the Redact icon from the top.

Step 3. To catch every occurrence, click Search, type the text you want gone (e.g. an account number), and select the matches. Or simply drag directly over any sensitive area to mark it.

Step 4. Click Apply to permanently remove the marked content, then choose Save → Save As Other to save the redacted copy.

The redaction steps are the same on Windows and Mac. On iPhone, iPad, and Android, UPDF can add a file-level password to lock a PDF on the go, though true redaction is best done on the desktop app.

Because this permanently deletes data, it's the method to use when you're learning how to redact a PDF for real sharing. Download UPDF for free to try redaction on a copy of your file — installation is free, and Pro features are available when you need watermark-free export or advanced tools.

Part 3. Method 2 — Black Out Text with Adobe Acrobat

Adobe Acrobat's Redact tool also removes the underlying data, so it qualifies as true redaction. The catch is cost and privacy: Acrobat Pro runs $239.88/year, and the free online redaction tool uploads your file to Adobe.

Step 1. Open the PDF in Adobe Acrobat and select All tools → Redact a PDF.

Step 2. Choose Redact text & images, then drag to select, or use Find text and redact to locate specific words across the document.

Step 3. Click Apply and confirm. Acrobat warns that the content will be permanently removed.

Step 4. Save the file. Keep an unredacted original, since the redacted data cannot be restored.

For a step-by-step comparison of the desktop and online routes, see how to redact in Adobe.

Part 4. Method 3 — Black Out Text in PDF with Preview (Mac, Free)

macOS Preview includes a real Redact tool that removes the selected content, not just covers it. It's the fastest free route on a Mac for low-volume redaction.

Step 1. Open the PDF in Preview.

Step 2. Click the Markup toolbar icon, then choose Redact (Preview warns that redacted content will be removed — click OK).

Step 3. Drag across each section of text you want blacked out.

Step 4. Choose File → Save. Preview finalizes the redaction on save.

Preview can't search-and-redact across a long file, so for a 40-page contract where a number repeats, a desktop tool with search is safer. On Windows, there's no built-in equivalent — use UPDF or Acrobat instead.

Part 5. Method 4 — Black Out Text in PDF Online (No Install)

Browser tools like Xodo or Smallpdf can redact text without an install. The trade-offs are privacy (the file leaves your device) and limits (free tiers often cap you at a couple of files before asking you to upgrade).

Step 1. Open the online redaction tool and click Select file to upload your PDF (some also import from Google Drive or Dropbox).

Step 2. Select the text you want to redact, then mark each section.

Step 3. Click Finish and confirm that the selected content will be removed.

Step 4. Download the finished file.

Because the upload is the whole risk here, keep online tools for documents that wouldn't hurt if a stranger saw them. For sensitive files, a local redact PDF workflow is the safer choice. If you'd rather compare browser options, see redact PDF online.

Part 6. Which Method Should You Use?

Every method below except the shape/black box performs true redaction. The differences that matter are platform, privacy, and cost:

For strong redaction with search, local-only processing, and no per-file cap, UPDF covers Windows and Mac in one workflow. On a Mac with only occasional needs, Preview is a solid free option.

Part 7. When Blacking Out Text Goes Wrong

The most common redaction failures aren't tool bugs — they're setup mistakes. Here's how to fix the ones people actually hit:

• "I drew a black box, but the text is still there." You covered the text instead of redacting it. Delete the shape and use a real Redact tool (UPDF, Acrobat, or Preview) so the data is removed, not hidden. See white out PDF for why fake white-out has the same flaw.
• "I redacted the visible page, but the name is still in the file." The same text can appear in metadata, bookmarks, or comments. After redacting, also sanitize the document to strip hidden data.
• "My scanned PDF won't let me select the text to redact." A scan is an image, so there's no selectable text layer. Run OCR first to make the text searchable, then redact.
• "The number repeats on many pages and I missed some." Manual dragging misses copies. Use Search & Redact (UPDF) or Find text (Acrobat) to catch every instance at once.

Part 8. FAQs

Conclusion

Blacking out text in a PDF only protects you if you remove the data instead of covering it — a black box can be peeled back, while true redaction is final. UPDF handles redaction locally on Windows and Mac with Search & Redact to catch every copy, Preview covers Mac users for free, and Adobe or online tools fit specific cases at higher cost or privacy risk. For more ways to lock down a file, see the full guide on how to protect PDF.

Download UPDF for free to try redaction on a copy of your file — installation is free, and Pro features are available when you need watermark-free export or advanced tools.