To crop and resize an image in Preview without distorting it, first crop away unwanted edges, then use Tools > Adjust Size and keep Scale proportionally selected. Cropping changes what remains in the frame; proportional resizing changes the image’s dimensions while preserving its original shape. Avoid entering unrelated width and height values with proportional scaling turned off, which can make the image look stretched. Apple’s Preview guide

Crop the image to keep the right composition

  1. Open the image in Preview. If the Markup toolbar is hidden, click Show Markup Toolbar, then click Rectangular Selection.
  2. Drag over the part of the image you want to keep. Adjust the selection so it frames the subject and excludes the areas you want removed.
  3. Click Crop in the Markup toolbar. Preview discards the parts outside the selection. Apple documents this crop workflow.

Cropping can change the image’s aspect ratio—for example, from a wide rectangle to a nearly square frame—because it removes content from the edges. It does not stretch the remaining subject. If you need a particular crop size, Preview’s Tools > Show Inspector includes a Crop Inspector that can display the selection dimensions in a chosen unit. Use that readout to guide the selection; the crop step itself is still a rectangular selection.

If you crop the wrong area, choose Edit > Undo Crop immediately. Apple also documents restoring an earlier image version through File > Revert To > Browse All Versions. If you may want the original composition later, consider making a copy before editing so you have a separate source file to return to.

Resize while preserving the image’s proportions

  1. With the image open, click Show Markup Toolbar if needed, then click Adjust Size. You can also choose Tools > Adjust Size.
  2. Check that Scale proportionally is selected. Enter the desired width or height; Preview updates the other dimension to retain the original proportions.
  3. Confirm the units beside the Width and Height fields. For a percentage-based resize, choose percent in the pop-up menu and enter a percentage. You can also choose a preset from Fit into; Preview may make one dimension smaller than the preset’s limit to preserve the image’s proportions. Apple describes these sizing controls and behaviors.

For example, if you have a landscape image and need it to fit within a maximum width and height, use Fit into or set one dimension with proportional scaling on. The result may not fill both limits exactly: preserving proportions means the image fits inside the requested bounds without being forced to match both. If the destination requires an exact rectangular shape, crop the image to that shape first, then resize proportionally.

What to do if the image still looks wrong

If the subject appears unusually wide or tall, reopen Adjust Size and verify Scale proportionally is selected. With that option off, independently entered width and height values can change the image’s shape. Selecting it again preserves the proportions from then on, but it cannot determine which composition or dimensions you intended; adjust one dimension and check the previewed values before applying the change.

If the image looks soft after making it larger, proportional scaling has prevented stretching but has not added original detail. For smaller dimensions without resampling, Apple says to deselect Resample image before changing width or height. For reducing file size, Apple’s separate instructions use Tools > Adjust Size, select Resample image, and enter a smaller value in Resolution; the displayed new size appears at the bottom of the dialog. These settings address different goals, so choose based on whether you need pixel dimensions, print sizing, or a smaller file.

Save the result and check the dimensions

After cropping and resizing, inspect the image at a useful zoom level and confirm the subject still looks natural. Use Adjust Size to check the resulting dimensions. Save the edited image when it is ready; if you need both the original and edited version, work on a duplicate so the original remains available independently.

Preview’s documented controls let you crop a rectangular area and resize proportionally. They do not provide a command in this workflow to stretch an image to fill an arbitrary width and height while also preserving all of its content: those requirements can conflict when the target shape differs from the source. For a no-stretch result, decide whether the priority is to preserve the whole frame with empty margins, or crop some content to match the target shape, then resize with Scale proportionally on.

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