How to Resize Multiple Images on Mac at Once

Pick the size before you start

Most batch jobs go wrong because the size isn't clear. Decide on the long side (the larger of width and height) rather than the width, so a portrait photo doesn't end up twice as tall as a landscape one.

• Email and messaging: about 1600px on the long side.
• Websites and online stores: the largest size the page shows, usually 1200–2000px.
• Instagram: 1080px wide.
• Slides and documents: 1280–1920px is plenty for a full-screen image.

Making images smaller is safe; making them larger adds no detail and only makes the file heavier. Always keep the originals until you've checked the results.

Method 1: Resize a batch in Preview

Preview applies one size to every image you select, and you can type an exact width or a percentage.

1. Copy the images into a new folder first. Preview saves its changes into the files you open, so working on copies keeps your full-size originals.
2. Select all the copies in Finder and press Command-O. They open together in one Preview window, with thumbnails in the sidebar. If you don't see the sidebar, choose View → Thumbnails.
3. Click any thumbnail, then press Command-A to select them all.
4. Choose Tools → Adjust Size. Enter a width in pixels, or switch the unit menu to percent to shrink every image by the same amount. Keep Scale proportionally and Resample image turned on, then click OK.
5. Close the window. Preview saves the resized images; if it asks, choose Save.

Percentages work best when your photos are different sizes. A fixed width works best when they're all the same orientation.

Method 2: Make smaller copies from Finder

On macOS Monterey and later, Finder can make resized copies without opening any app.

1. Select the images in Finder.
2. Right-click and choose Quick Actions → Convert Image.
3. Pick a Format and an Image Size: Small, Medium, Large, or Actual Size.
4. Click Convert. The copies appear next to the originals.

It's the quickest built-in option, but the three sizes are presets, so you can't ask for exactly 1600px. If the goal is a smaller file rather than a specific size, see how to compress images on Mac for the quality settings that matter.

Method 3: Exact sizes for hundreds of files with sips

Every Mac includes sips, a command-line image tool. It resizes any number of files to an exact size and is the best built-in choice for large batches. Open Terminal and run:

cd ~/Desktop/photos
mkdir -p resized
setopt nullglob nocaseglob
sips -Z 1600 *.{jpg,jpeg,png} --out resized

• cd moves into the folder with your images. Type cd and drag the folder onto the Terminal window to fill in its path.
• -Z 1600 sets the long side to 1600px and keeps the proportions. Use --resampleWidth 1200 instead to give every image the same width.
• --out resized writes the new files into the resized folder and leaves the originals untouched.
• The setopt line lets the command match .JPG as well as .jpg, and skip file types the folder doesn't have instead of stopping with an error.

One catch: sips also enlarges images that are smaller than the size you give it, so pick a size below your smallest photo, or move small images out of the folder first.

Method 4: Resize from the right-click menu with FinderBuddy

If you resize images every week, FinderBuddy adds Resize Image to Finder's right-click menu. Select one image or a few hundred, right-click, and choose FinderBuddy → Resize Image.

• Type an exact width, height, or percentage. The aspect ratio is kept unless you set both.
• Resized copies are saved next to the originals with the size in the name, like vacation-1600w.jpg.
• It works on JPG and PNG files, and everything is processed on your Mac.

You can compress or convert the same batch right after, from the same menu. See pricing or read the setup guide.

Which method should you use?

• A handful of photos, exact size: Preview.
• Smaller copies fast, size not critical: Finder's Convert Image.
• Hundreds of files, exact size, comfortable with Terminal: sips.
• Exact sizes from the right-click menu, every week: FinderBuddy.

Photos from an iPhone are often HEIC files. If a site won't accept them after resizing, see how to convert HEIC to JPG on Mac. And if you need to rename the batch afterwards, see how to batch rename files on Mac.