PDFs and conversion

How to resize images on a Mac

Updated 25 October 2026 · 3 min read

Resize one image or a batch with Preview, Finder's Convert Image or sips, and how Orrel resizes, compresses and strips location data into new copies.

Photos from a phone or camera are often several thousand pixels across, far more than an email, a web form or a document needs. Shrinking them makes them quicker to send and upload. macOS has three built-in ways, and the main thing to watch is whether each one changes your original.

Preview: Adjust Size

1. Open the image in Preview. If you want to keep the original unchanged, choose File › Duplicate first and work on the copy.
2. Choose Tools › Adjust Size.
3. Pick a preset from "Fit into", or type a width or height. The units menu offers pixels, percent, inches and centimetres.
4. Leave Scale proportionally ticked so the image is not stretched, and Resample image ticked so the pixel count actually changes.
5. Click OK. The dialog shows the resulting file size before you commit.

Preview: a batch at once

Select several images in Finder and press ⌘O to open them in one Preview window. Show the sidebar, click any thumbnail and press ⌘A to select them all, then choose Tools › Adjust Size. The setting applies to every selected image.

The trap. Preview saves changes to the files you opened. Resizing a batch this way replaces your originals with the smaller versions when you close the window. Copy the images to a new folder first, or use File › Export Selected Images to save copies elsewhere.

Finder: Convert Image

On macOS 12 Monterey and later, select one or more images, Control-click and choose Quick Actions › Convert Image. Choose a format (JPEG, PNG or HEIF), an Image Size of Small, Medium, Large or Actual Size, and whether to keep the metadata. New files are written beside the originals, which are left alone. The sizes are presets rather than exact pixel dimensions.

sips in Terminal

sips comes with macOS. This makes copies of every JPEG in a folder with the longest side no more than 1,600 pixels, saved into a resized folder:

cd ~/Desktop/photos
mkdir resized
sips -Z 1600 *.jpg --out resized

Without --out, sips overwrites the originals. -Z keeps the proportions; use --resampleWidth 1200 to set an exact width instead.

How Orrel does it

Control-click images in Orrel, drop them on Orrel's Dock icon, or choose Orrel from Finder's Quick Actions, then choose Resize from the ring.

• By longest side or by half. Pick 3840, 2560, 1920, 1280 or 800 pixels for the longest side, or 50%. Proportions are kept and the photo's rotation is applied, so it stays the right way up.
• New copies. Each resized image is saved beside the original with the size in its name, such as beach 1920px.jpg. Originals are never changed.
• Never enlarges. An image already smaller than the size you choose is left alone, and Orrel says so.
• Compress. High, Medium or Small quality re-saves photos as JPEG (or HEIC when they have transparency), and keeps the result only if it is smaller.
• Remove Metadata. Strips camera details, dates and GPS location from a copy, keeping only the orientation.

Where Orrel stops

Orrel's sizes are presets. It cannot resize to an exact width and height, crop, or enlarge an image, and the only percentage is 50%; Preview's Adjust Size or sips covers those. Resize keeps the metadata, so remove it separately if location matters. Orrel is not a photo editor, so colour, exposure and sharpening stay with Photos or Preview.