How to blur a screenshot on Mac

Command + Shift + 4. You already know that. If you need the capture keys spelled out, use how to screenshot on a Mac. Preview is where people get clever and then leak.

macOS is good at capturing a region. It is average at pretending to be a redaction suite. You do not need Pixelmator or Photoshop for a Slack snip. You need a filled rectangle, a PNG, and the discipline not to attach the file sitting on the Desktop named Screen Shot 2026-08-15 at 9.12.04 AM.png next to the redacted copy.

How do I redact a screenshot in Preview?

1. Open the PNG in Preview (double-click, or File → Open).
2. Show the Markup toolbar. Rectangle tool. Fill color black. Line color black so you do not leave a halo.
3. Cover the text. Include padding. Zoom with Command + plus.
4. Duplicate first if you still need a clean original, then export or save the covered copy.

A white rectangle with 40% opacity is a decoration. Anyone can put the file in another editor and crank contrast. Black fill, full opacity. If Markup’s rectangle still looks translucent, you picked the wrong fill. Fix it before you drag the file into Messages.

Preview’s annotate tools include a highlighter. Do not use it as a privacy tool. It is for calling attention to a sentence, which is the opposite of hiding one.

Can I blur a screenshot on Mac without Photoshop?

Preview is not a blur studio. Photos has filters that look cinematic and do nothing useful to a 12-point email. If you want blur rather than a bar, skip the filter gallery. Safari can load BlurThis, you drop the screenshot on the canvas, paint blur or a bar, and download. Drag that file into Slack. Done.

Continuity Camera and iPhone-to-Mac photo imports are a different pipeline. Those files may still carry EXIF if they began life as Camera shots, not as macOS screenshots. A screenshot from Command + Shift + 4 is usually a clean PNG on disk. Still send the edited export, not both files in one zip “for context.”

What about the menu bar?

VPN city, meeting title, unread badge with a person’s name, a Focus mode that implies you are in a clinic. Crop the menu bar or bar it. Same class of mistake as a Windows toast. The notification that ruined the screenshot is the longer version of this warning.

Stage Manager and multiple spaces make accidental chrome more likely. You meant to grab a dialog. You also grabbed a sliver of Mail. Check the edges at full size before you hit send. Command + Shift + 4 already lets you drag a tight rectangle. Use that at capture time when the secret is in a corner.

Quick Look is not an editor

Spacebar Quick Look is for checking the shot. Markup from Quick Look can still save. Confirm you saved a new file. Confirm Finder is not highlighting the original. People attach from the wrong recents list in the Mail composer all afternoon.

Command + Shift + 5 opens the screenshot toolbar: capture window, capture region, record. Useful. Still not a redaction suite. The floating thumbnail in the corner is a trap. People Markup it with a highlighter, then click Done, then attach the Desktop original anyway because Mail’s recents list prefers the larger file. Watch which icon you pick.

Grab.app still exists in Applications → Utilities for people who learned Macs before the toolbar. Same rule. Capture, then Preview or a browser canvas. Do not confuse “I selected a window” with “I covered the token in the URL bar of that window.”

Format

Stay on PNG for a baked bar. If you export JPEG from Preview, keep quality high, and understand chat apps may crush it anyway. Starting from PNG is still the better habit. More on why mushy JPEG is a bad redaction container: save as PNG, not a mushy JPEG.

Windows at the other desk is Win + Shift + S plus Paint or a browser tab. The philosophy matches. Only the keys change. If you write internal docs for a mixed fleet, say “cover the pixels, export a new file” instead of “use Preview,” or half the company will nod and do nothing.