How to Crop an Image on Mac (Preview + Photos)

Every Mac ships with three croppers: Preview for files, Photos for your library, and Quick Look for the crop-without-opening-anything move. None needs installing and each fits a different moment. Here's the fastest path in all three, plus how to undo a crop after you've saved it.

Crop in Preview (files, screenshots, downloads)

1. Open the image in Preview.
2. Drag a rectangle around the part you want to keep — the default tool is rectangular selection, so just drag. The selection shows its pixel dimensions as you drag, which is handy when a target size matters.
3. Adjust by dragging the handles on the selection's edges. Hold Shift to force a square.
4. Choose Tools → Crop or press Cmd + K.
5. Save with Cmd + S.

Two safety nets: Cmd + Z undoes the crop while the file is open, and even after saving, File → Revert To → Browse All Versions… can restore the pre-crop image, because macOS keeps document versions for files you edit locally. If the image is a PNG screenshot, cropping doesn't recompress it — you lose nothing but the trimmed pixels.

Crop in Photos (your library, non-destructive)

1. Double-click the photo and click Edit in the toolbar (or press Return).
2. Click the Crop tab at the top.
3. Drag the frame's corners freely, or pick a preset under Aspect on the right — Square, 16:9, 4:3, 3:2, and the rest. Freeform removes the constraint.
4. Click Done.

Photos crops are non-destructive: reopen Edit → Crop and drag the frame back out, or use Revert to Original, at any point — years later included. The crop syncs through iCloud Photos to your other devices. This is also where to straighten a tilted horizon: the dial next to the crop frame rotates in fine degrees and crops the edges automatically.

Crop from Quick Look (no app at all)

For a file you just want trimmed and moved on from — select it in Finder, press Space, click the markup icon (the pencil tip) in the Quick Look toolbar, then click the crop button. Drag the frame, press Done, and the file is saved cropped without ever opening an app. It's the fastest route for a one-off screenshot; the trade-off is fewer niceties (no pixel readout, no aspect presets).

Which one when

• Preview — anything in Finder, exact pixel control, and batch work (open several images at once and walk the sidebar).
• Photos — anything in your photo library, aspect ratios, and crops you might want to undo someday.
• Quick Look — the ten-second trim when opening an app feels like overkill.

A caution about cropping PDFs

The same Cmd + K works when a PDF is open in Preview, but it behaves differently in one important way: on a PDF, Crop sets the page's crop box — a display instruction — rather than deleting the content outside it. The page looks trimmed in most readers, but the cropped-away material is still in the file, and other software can restore the full page. For tidying your own reading view that's fine; for removing something sensitive before sharing, it absolutely isn't — that calls for real redaction, not a crop. With images there's no such subtlety: cropped pixels are removed when you save.

Batch cropping follows the same logic as batch anything in Preview: open all the images at once (select them in Finder and press Cmd + O), and they line up in one window's sidebar. Crop the first, click the next thumbnail, repeat — one window, one rhythm, no app juggling. Preview keeps each file's changes separate, so a stray crop only ever affects the image it was made on.

Cropping to exact dimensions

Need 1200×630 exactly? Make a rough crop, then use Preview's Tools → Adjust Size… to hit precise pixels — the full workflow is in how to resize an image on Mac.