How to Resize an Image on Mac

Learn how to resize an image on your Mac in Pages, or by using the Preview app

What to Know

  • You can change the size of almost any standard image file format in the Preview app already included with your Mac.
  • Open your image with the Preview app: Select Tools > Adjust Size, then enter the new dimensions for your image.

This article explains how to change the size of an image on a Mac, either when using the Pages app or through Preview.

How Do I Resize an Image?

The most direct way to resize an image on a Mac is through Preview, which is the default image viewing app. It’s not ideal for more complex image adjustments, but it’s a quick and easy way for something like resizing. Preview is able to open and adjust most any standard image file, such as .JPEG, .JPG, .TIFF, .PNG, etc.

Making an image larger will not increase the resolution, meaning if you try to resize a smaller image (for example 600x800) to something much larger (like 3000x4000), it will probably look blurry or fuzzy. Reducing the size of an image will not cause this problem.

  1. Open the image file in Preview.

    Open the image in Preview
  2. Select Tools from the menu bar at the top of the screen, and then select Adjust Size.

    Cat photo in Preview with Adjust Size highlighted
  3. This will pull up the Image Dimensions menu with an assortment of different options.

    Image Dimensions menu highlighted in Preview
  4. You can change the measurement type by clicking the pulldown menu on the right, which should show pixels by default.

    Measurement type highlighted in Preview image dimensions
  5. Depending on the measurement type you need or are familiar with, you can select pixels, percent, inches, cm (centimeters), mm (millimeters), or points.

  6. Typing in a new value in either the Width box will change the dimensions of the image’s width, and Height will change the height.

    Width and Height measurements highlighted in Preview image dimensions
  7. If Scale proportionally is checked off you only have to change the values in one of the two boxes as the other one will change automatically to fit.

    Scale proportionally highlighted in Preview image dimensions
  8. Click OK to finish resizing your image. If everything looks good don’t forget to save when you’re finished!

    OK highlighted in Preview image dimensions

How Do I Resize a JPEG Image?

You can also use Preview to resize a JPEG image on your Mac by following the same steps as above.

  1. Open the .JPEG in Preview.

    Open jpeg
  2. Select Tools > Adjust Size to pull up the Image Dimensions menu.

    Adjust Size highlighted in Preview
  3. Typing in a new value in the Width box will change the dimensions of the image’s width, and Height will change the height.

    Preview image dimensions with Width and Height highlighted
  4. If Scale proportionally is checked off you only have to change the values in one of the two boxes as the other one will change automatically to fit.

    Preview image dimensions with Scale Proportionally highlighted
  5. Click OK to finish resizing your image.

    Preview image dimensions with OK highlighted

How Do I Change the Size of an Image in Pages on Mac?

Resizing an image in Pages is almost as straightforward as it is in Preview, though the menus and possible methods are notably different.

Inserting an image or changing the dimensions of an image in a complete (or near-complete) document could cause tables or paragraphs to shift.

  1. Click the image in your Pages document and select the Arrange tab in the menu column on the right-hand side..

    Image in pages document with the Arrange tab highlighted
  2. Scroll down to the Size portion of the menu.

    Pages Arrange tab with the Size section highlighted
  3. Enter a new value in either the Width and Height box and press return.

    Width and Height box highlighted in Pages Arrange size menu
  4. If Constrain proportions is checked off, you only have to change the value of Width or Height (not both) to change the overall dimensions of the image.

    Constrain Proportions highlighted in Pages Arrange tab
  5. Alternately, you can manually resize the image with your mouse or trackpad until it fits the document the way you want it to.

  6. With the image selected, move your cursor to one of the small white boxes displayed on any of the corners or sides. The cursor should change from a single arrow to a double-sided arrow.

  7. When the double-sided arrow appears, click and drag the edge of the image to make it larger or smaller.

    Manual image resizing in Pages with click and drag box highlighted
  8. If Constrain proportions is checked off the image will resize while automatically retaining the same proportions (i.e. it won’t “stretch” out of proportion while you resize it).

FAQ
  • How do I resize an image on Mac in iPhoto?

    To resize an image using the Mac's Photos app, open Photos and select your image. Click File > Export [1] Photo (or however many you're exporting). Under Size, select a preset (Full Size, Large, Medium, or Small). Or, select Custom to enter a maximum width or height. Click Export when you've made your selections.

  • How do I resize an image on Mac for wallpaper?

    To resize an image to use as wallpaper, select the Apple menu > System Preferences > Desktop & Screen Saver. Click Desktop and navigate to the picture you want to use. Click the image's thumbnail and choose Fill Screen, Fit to Screen, or Stretch to Fit to have your image appear as you desire.

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