MotionShineShort answer: open the screenshot in Preview, show the Markup toolbar, click the Rectangular Selection button, drag over the part to keep, then click Crop. Apple's Preview guide gives those steps. If you have not taken the screenshot yet, press Shift-Command-4 and drag over only the area you want, so there is nothing to crop.
Apple facts are from Apple Support pages, checked on 24 October 2026.
Crop in Preview
Apple's steps:
- Open the image in Preview.
- If the Markup toolbar is not showing, click Show Markup Toolbar. Then click Rectangular Selection.
- Drag to select the area you want to keep. To see dimensions, choose Tools > Show Inspector and use the Crop Inspector.
- Click Crop in the Markup toolbar.
Changed your mind? Apple says to choose Edit > Undo Crop straight away. Later, choose File > Revert To > Browse All Versions and restore the version from before the crop. Apple's page does not list a keyboard shortcut for crop.
Crop to an exact size
Apple's Preview page gives two tools for size. They do different jobs, so it helps to know which one you need.
- Crop Inspector shows the size of your selection while you drag. Choose Tools > Show Inspector, click the Crop Inspector button, then pick a unit of measurement. Use it to check that the box is the size you want before you click Crop. Apple's page describes it as a place to see the selection's dimensions. It does not say you can type values into it, so for typed pixel values use the browser cropper below.
- Adjust Size changes the whole picture, not the area. Click Adjust Size in the Markup toolbar, or choose Tools > Adjust Size. Enter a width and height, or pick a size from the Fit into menu. Tick Scale proportionally to keep the shape. Apple also says to untick Resample image before changing the dimensions if you want to shrink the picture without losing detail.
A common order is to crop first, then use Adjust Size. Cropping removes the parts you do not want. Adjust Size then makes what is left the right width for a blog post, a document or an email.
Crop from the thumbnail right after you capture
Apple's screenshot page says that after a capture, a thumbnail shows briefly in the bottom-right corner. Clicking it opens a window where you can mark up the screenshot, and you can also swipe it right to save it at once, or drag it into a document, email, note or Finder window. Several third-party guides say the crop button is in that same markup window. Apple's page does not name a crop button there, so treat this as a common route that is not described by Apple. It is quick when you have just taken the shot and still see the thumbnail.
If the thumbnail never appears, open Options in the Shift-Command-5 toolbar and check that Show Floating Thumbnail has a checkmark. The thumbnail only stays for a few seconds, so for older screenshots use Preview.
Crop in Photos
If the screenshot is in your Photos library, Apple's steps are:
- Double-click the photo.
- Click Edit, then Crop.
- Drag the selection rectangle around the part to keep, or pick a fixed shape such as Square, 4:5 or 16:9 in the sidebar, or Custom.
- Click Done or Save Changes. To undo, use Revert to Original, or Reset to remove only the crop.
Apple warns that cropping a photo in Photos changes its appearance everywhere in Photos, including albums, slideshows and projects. To avoid that, duplicate the photo first and crop the copy.
Keep the original
Cropping throws away the area outside your selection. Apple's Preview page says to choose Edit > Undo Crop right after, or to restore an earlier version with File > Revert To > Browse All Versions. That page does not say whether Preview keeps your original file on disk after you save, so do not rely on it as a backup.
The safe habit is general advice, not an Apple instruction: duplicate the screenshot in Finder before you crop, and crop the copy. In Photos, Apple gives the same advice for a different reason, because a crop shows everywhere that photo is used.
Which method should you pick?
| Situation | Best choice |
|---|---|
| You have not taken the shot yet | Shift-Command-4 and drag |
| Quick trim of a saved file | Preview, Rectangular Selection, Crop |
| Screenshot lives in your Photos library | Photos, Edit, Crop (duplicate first) |
| Need a specific shape or typed pixel values | The free browser cropper |
| Many screenshots, same crop | The free browser cropper, batch mode |
| Need to hide a detail, not cut it off | Blur it instead |
Crop with a free browser tool
The image cropper on this site runs in your browser. Its page says it accepts PNG, JPG, WebP and HEIC, and you can paste a screenshot with Command-V. Drag the box, pick a shape or a social size such as 1080 x 1080, or type exact pixel values, then click Download the picture. The page says nothing is uploaded. It can also crop many pictures the same way at once, which is handy for a set of screenshots.
Better: capture only the part you want
Apple's screenshot page gives two ways to capture a portion:
- Press Shift-Command-4, move the crosshair to where you want to start, then drag and release.
- Press Shift-Command-5, click the portion tool, drag the frame to the right place or resize its edges, then click Capture.
After a capture, a thumbnail floats in the bottom-right corner for a few seconds. Apple says you can click it to open a window where you can mark up the screenshot. Every shortcut is in Mac screenshot shortcuts. To hide private details instead of cutting them off, see how to blur text in a screenshot.
Cropping a video instead
For a screen recording, the same idea applies to video. The free crop video tool works in the browser. To record just one area, how to screen record on Mac covers the Screenshot app. MotionShine, by the maker of this site, is a free Mac screen recorder with a full editor, but it is not an image cropper, so use the tools above for screenshots.
FAQ
How do I crop a screenshot on a Mac?
Open it in Preview, click Rectangular Selection in the Markup toolbar, drag over the part to keep and click Crop.
Is there a shortcut for crop in Preview?
Apple's page does not list one. Use the Crop button in the Markup toolbar.
Can I undo a crop?
Yes. Choose Edit > Undo Crop right away, or restore an earlier version from File > Revert To > Browse All Versions.
How do I take a screenshot of just part of the screen?
Press Shift-Command-4 and drag over the area, per Apple Support.
How do I crop a screenshot to an exact size?
In Preview, the Crop Inspector shows the size of your selection in the unit you pick. For typed pixel values, use the free image cropper, which lets you enter them.
What is the difference between Crop and Adjust Size?
Crop removes part of the picture. Adjust Size changes the width and height of the whole picture, as described on Apple's Preview page.
Can I crop a screenshot right after I take it?
Click the thumbnail in the corner within a few seconds. Apple says it opens a window for markup. Many guides say the crop control is there too, but Apple's page does not name it.
Does cropping in Photos change the original?
Apple says it changes the photo's appearance everywhere in Photos. Duplicate it first to keep the original, or use Revert to Original.
