How do you crop on a Mac?

Open the picture in Preview, show the Markup toolbar, choose Rectangular Selection, drag over the part to keep, and click Crop or choose Tools > Crop. For photos in your library, use Edit > Crop in the Photos app.

Why is Crop greyed out in Preview?

Usually because there is no rectangular selection yet, or another Markup tool is active. Draw a box with Rectangular Selection and try again. If the file is locked or read-only, duplicate it and crop the copy.

What is the keyboard shortcut to crop in Preview?

Open the Tools menu with a selection drawn: the shortcut is shown next to Crop. Shortcuts can differ with your keyboard layout, so the menu is the reliable place to check.

Can Preview crop to an exact size in pixels?

Yes, with the Inspector. Choose Tools > Show Inspector, set the unit to pixels and drag until the selection shows the size you want. Then crop.

How do I resize a picture on a Mac instead of cropping it?

In Preview, choose Tools > Adjust Size and type a new width or height. Resizing keeps the whole picture and changes its pixel size. See crop vs resize.

Does cropping in Preview lower the quality?

Cropping only removes pixels. But saving a JPEG again adds a little compression each time, so crop from the original and save once. See does cropping reduce image quality.

How to crop a photo on Mac: Preview, Photos and screenshots

Updated October 24, 2026 · 5 min read

Short answer

Open the picture in Preview, click the Markup button, pick the Rectangular Selection tool, drag over the part you want to keep, then choose Tools > Crop. Undo straight away with Edit > Undo Crop. For pictures in your Photos library, open the photo, click Edit, then Crop.

Which Mac app to use

Crop a JPG, PNG or screenshot file
Use
Preview
Why
Opens any image file, shows the exact selection size
Crop a photo in your library
Use
Photos
Why
Fixed ratios like Square, 4:5 and 16:9, and you can revert
Grab only part of the screen
Use
Shift‑Command‑4
Why
Crops while you take the screenshot
Crop many photos to one size
Use
A batch tool
Why
Preview and Photos crop one picture at a time

You want to	Use	Why
Crop a JPG, PNG or screenshot file	Preview	Opens any image file, shows the exact selection size
Crop a photo in your library	Photos	Fixed ratios like Square, 4:5 and 16:9, and you can revert
Grab only part of the screen	Shift‑Command‑4	Crops while you take the screenshot
Crop many photos to one size	A batch tool	Preview and Photos crop one picture at a time

How to crop a picture in Preview

01Open the picture in Preview. If it opens in another app, right-click the file and choose Open With > Preview.
02If you do not see the editing tools, click the Markup button (a pen tip in the toolbar) to show the Markup toolbar.
03Click the selection tool, the dotted rectangle, and choose Rectangular Selection.
04Drag over the part of the picture you want to keep. Drag the handles on the edges to adjust it.
05Click the Crop button in the Markup toolbar, or choose Tools > Crop. The Tools menu also shows the keyboard shortcut next to Crop.
06Choose File > Save. Preview saves over the file, so use File > Duplicate first if you want to keep the original.

See the exact size while you select

Choose Tools > Show Inspector, then open the crop section of the Inspector. It shows the width and height of your selection, and you can pick the unit, for example pixels. This is the easiest way to crop to a size such as 2000 x 2000 on a Mac without extra software. For exact sizes in general, see how to crop a photo to a specific size in pixels.

Crop is greyed out in Preview: how to fix it

There is no selection yet. Crop only works once you have drawn a box with the Rectangular Selection tool. Draw one, then try again.
The wrong tool is active. If a shape, text or sketch tool is selected, click the selection tool again and redraw the box.
The file cannot be changed. A locked file, or one on a read-only drive or in a shared folder, may not let Preview save. Duplicate it to your desktop and crop the copy.
It is a PDF, not a picture. PDFs crop differently, page by page. Apple has separate steps for cropping a PDF in Preview.

How to crop a photo in the Photos app on Mac

01Open Photos and double-click the photo.
02Click Edit in the toolbar, then Crop.
03Drag the frame around the part you want to keep, or pick a shape in the sidebar: Square, 4:5 for prints, 16:9 for video, or Custom to type your own ratio.
04Use Flip, the orientation buttons or the Straighten slider if you need them. Auto crops and straightens in one click.
05Click Done to save.

A crop in Photos changes the picture everywhere in your library, including albums and slideshows. To keep both, duplicate the photo first and crop the copy. You can always go back with Revert to Original.

How to crop a screenshot on Mac

The quickest crop is not to capture the whole screen at all. Press Shift-Command-4, then drag over just the area you want. Release, and the screenshot is saved to your desktop as a PNG file. Press Esc to cancel. Press the Space bar after Shift-Command-4 to capture one window instead.

Already took a full-screen shot? Click the thumbnail that appears in the bottom-right corner to open it for markup, or open the file in Preview and crop it with the steps above.

How to change the size of a screenshot

Cropping removes part of the screenshot. To make the whole screenshot smaller, open it in Preview, choose Tools > Adjust Size, keep Scale proportionally ticked and type a smaller width. Mac screenshots are PNG files, which are large for photos and screens with gradients. If you need a smaller file, convert PNG to JPG.

Undo a crop on Mac

Straight away in Preview: choose Edit > Undo Crop.
Later in Preview: choose File > Revert To > Browse All Versions and pick a version from before the crop.
In Photos: open the photo, click Edit, then Revert to Original.

More ways, including other apps, are in how to undo a crop.

Crop or resize many pictures at once

Preview can resize several images at the same time: open them in one window, select them in the sidebar and choose Tools > Adjust Size. Apple documents this for resizing and rotating, not for cropping, so each crop is still done by hand. To crop a batch of product photos to one exact size, see how to crop multiple photos at once.

Frequently asked questions

How do you crop on a Mac?: Open the picture in Preview, show the Markup toolbar, choose Rectangular Selection, drag over the part to keep, and click Crop or choose Tools > Crop. For photos in your library, use Edit > Crop in the Photos app.
Why is Crop greyed out in Preview?: Usually because there is no rectangular selection yet, or another Markup tool is active. Draw a box with Rectangular Selection and try again. If the file is locked or read-only, duplicate it and crop the copy.
What is the keyboard shortcut to crop in Preview?: Open the Tools menu with a selection drawn: the shortcut is shown next to Crop. Shortcuts can differ with your keyboard layout, so the menu is the reliable place to check.
Can Preview crop to an exact size in pixels?: Yes, with the Inspector. Choose Tools > Show Inspector, set the unit to pixels and drag until the selection shows the size you want. Then crop.
How do I resize a picture on a Mac instead of cropping it?: In Preview, choose Tools > Adjust Size and type a new width or height. Resizing keeps the whole picture and changes its pixel size. See crop vs resize.
Does cropping in Preview lower the quality?: Cropping only removes pixels. But saving a JPEG again adds a little compression each time, so crop from the original and save once. See does cropping reduce image quality.

Sources

Apple: Crop, resize, or rotate an image in Preview on Mac, checked October 24, 2026.
Apple: Crop, extend, reframe, and straighten photos and videos on Mac, checked October 24, 2026.
Apple: Take screenshots or screen recordings on Mac, checked October 24, 2026.

Rules change. Check the source before relying on a figure.

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