How to change an image size in Mac and Windows

What You’ll Learn

How to resize an image using built-in tools on both Mac and Windows computers.

Why It Matters

Resizing images helps them load faster on your website, keeps file sizes manageable, and ensures they look good across devices. It's especially useful when uploading banners, thumbnails, or gallery photos.

Step-by-Step Instructions

1. Change Image Size on Mac (Using Preview)

1. Double-click the image to open it in Preview.
2. If it opens in another app, right-click the file and choose Open With > Preview.
3. In the top menu bar, click Tools and then Adjust Size….
4. In the popup window, change the Width and Height using:
   • Pixels
   • Inches
   • Percent
5. Make sure Scale proportionally is checked to keep the image from stretching.
6. Click OK to apply the changes.
7. Save the image by pressing Command + S or going to File > Save.

2. Change Image Size on Windows (Using Photos App)

1. Double-click the image to open it in the Photos app.
2. If it opens in another app, right-click and choose Open With > Photos.
3. Click the three-dot menu (•••) in the top-right corner.
4. Select Resize from the dropdown.
5. Choose one of the preset options, or click Define custom dimensions to enter your own pixel size.
6. Click Save resized copy to create a new file with the new size (your original stays untouched).

Troubleshooting Tips

• Image looks blurry after resizing

  Try resizing to a size closer to the original dimensions. Enlarging a small image too much can reduce its quality.

• Changes not saving

  Make sure you're clicking the correct save option. On Windows, choose “Save resized copy”; on Mac, use Command + S or File > Save.

• Image stretched or squished

  Always keep “Scale proportionally” checked when resizing to maintain the correct aspect ratio.