# How to Blur Part of a Screenshot on Mac (So It Can't Be Un-Blurred)

> macOS Markup has no blur tool. Here's how to blur, pixelate or black out part of a screenshot on Mac, and which one can't be guessed back.

Published: 2026-10-05
Author: Elisei Nicolae
Source: https://snapix.app/blog/how-to-blur-part-of-a-screenshot-mac/

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You're about to send a screenshot, and there's something in it nobody else should see: an email address, a sign-in code, a customer's name. The screenshot tool on your Mac can't blur it. Here's how to blur part of a screenshot on Mac in a few seconds, and which kind of blur actually keeps a secret.

## Quick, easy blur with Snapix

[Snapix](/) is a screenshot app for Mac with three ways to hide things right in its editor: Pixelate, Blur and Black. Capture, press one key, drag over the private part, and the image you share already has it hidden. It all happens on your Mac, and nothing is uploaded.

## How to blur part of a screenshot on Mac

1. **Capture the screen.** Press <kbd>⇧⌘4</kbd> and drag over the area you need. A preview slides into the corner of the screen. Hover it and click **Edit**. Already have the image? Control-click it in Finder and choose **Open With ▸ Snapix**.
2. **Choose how to hide it.** Press <kbd>P</kbd> for Pixelate, <kbd>B</kbd> for Blur or <kbd>X</kbd> for Black. All three share one slot in the toolbar, and its menu can switch a box you've already drawn.
3. **Drag over what's private.** One drag covers one field, and one tall drag covers a whole column. You can move and resize a box afterwards, and the **Intensity** slider makes Blur and Pixelate stronger.
4. **Click Done.** The finished image is on your clipboard, ready to paste into a chat or an email (<kbd>⌘C</kbd> does the same). Prefer a file? Click **Save as…** instead.

<figure>
  <img
    src="/images/snapix-pixelate-blur-black-picker.webp"
    width="1662"
    height="654"
    loading="lazy"
    decoding="async"
    alt="The Snapix editor on Mac with a customer table open: the Email and Phone columns are pixelated, and the redact menu under the toolbar lists Pixelate (P), Blur (B) and Black (X), with the pointer on Blur"
  />
  <figcaption>Pixelate, Blur and Black share one slot in the Snapix toolbar. Here the Email and Phone columns are pixelated, and the menu is about to switch to Blur.</figcaption>
</figure>

**Tip:** Your email address is rarely on screen just once. It's in the header, the address bar and the notification in the corner. Press <kbd>⌘F</kbd> in the editor and type it. Snapix finds every place it appears in the picture, so you can cover them all.

## Pixelate, Blur or Black: which one should you use?

All three stop people from reading a detail at a glance. Only one stops a computer.

<figure>
  <picture>
    <source
      media="(max-width: 600px)"
      srcset="/images/snapix-pixelate-blur-black-compared-narrow.webp"
      width="716"
      height="584"
    />
    <img
      src="/images/snapix-pixelate-blur-black-compared.webp"
      width="1288"
      height="428"
      loading="lazy"
      decoding="async"
      alt="The same sign-in code hidden three ways in Snapix: Pixelate (P) and Blur (B) are marked 'Can be guessed back', Black (X) is marked 'Nothing left to guess'"
    />
  </picture>
</figure>

- **Pixelate** turns the area into big squares. Use it for names in a list, faces in the background, or anything that just needs to look tidy.
- **Blur** softens it, like frosted glass. Use it for clutter, other people's messages and busy backgrounds.
- **Black** covers it with a solid box. Use it for passwords, sign-in codes, card and account numbers, API keys and home addresses.

The rule we use ourselves is simple. **If it would hurt if someone guessed it, use Black.**

## How to blur a screenshot on Mac without an app

The Markup tools built into macOS can't blur or pixelate. They can draw a black box, though, and that's the safest choice anyway.

1. Press <kbd>⇧⌘4</kbd>, drag over the area, then click the thumbnail before it slides away. For an image already on your Mac, open it in Preview and click the Markup button.
2. Click **Shapes** and choose the rectangle.
3. Drag it over the private part and resize it with the handles.
4. Set **Fill Color** and **Border Color** to black.
5. Click **Done**. Once the image is saved, the box is part of it.

Need a real blur? Our free [Annotate Screenshot](/tools/annotate-screenshot/) tool blurs, pixelates or covers part of a screenshot with a solid box, right in your browser.

**Note:** A PDF works differently. A box drawn on a PDF can be moved, and the text under it can still be copied, so use Preview's **Redaction Selection** tool, which removes the text itself.

## Frequently asked questions

### Can blurred text be unblurred?

Sometimes. Nobody can take a blur off, but if the hidden text is short and predictable, like a code or a card number, a computer can blur every possible answer the same way and keep the one that matches. For anything secret, use a solid black box.

### Does the Mac screenshot tool have a blur option?

No. Markup, the editor behind the screenshot thumbnail and Preview, can draw shapes, text and signatures, but it can't blur or pixelate. Its closest tool is a rectangle filled with black. Once you save the image, the box becomes part of it.

### Is pixelating safer than blurring?

They're about the same. Both hide a detail from anyone looking at the picture, which is enough for names, faces and busy backgrounds. For passwords, sign-in codes and card numbers, use a solid black box.

### Does Snapix upload my screenshots?

No. Capturing, blurring and reading text all happen on your Mac. Your Recent Captures (**⇧⌘S**) stay on your Mac too, encrypted, so you can change a blur later.