How to Resize a Photo on Mac: 5 Free Methods

Your Mac already has everything you need to resize a photo. Preview handles single images in under 10 seconds. Automator batch-resizes an entire folder with a right-click. The sips command does it from Terminal without opening anything. And if you want a zero-setup option that works in any browser, Pixotter resizes photos client-side — no install, no upload.

Here are five methods to resize photos on Mac, ordered from quickest to most powerful. For a cross-platform overview with Windows, mobile, and CLI methods, see our complete photo resize guide. If you are resizing on an iPhone instead, jump to how to resize a photo on iPhone.

Method 1: Preview (Built-in, Free)

Preview ships with every Mac and uses Lanczos resampling — one of the sharpest downscaling algorithms available. For single images, this is the fastest native option.

Steps (macOS Sonoma 14 / Sequoia 15):

1. Right-click your photo in Finder → Open With → Preview.
2. Go to Tools → Adjust Size (keyboard shortcut: Cmd+Option+I).
3. In the dialog that opens, enter your target Width or Height in pixels. Make sure Scale proportionally is checked — this preserves the aspect ratio so your photo does not stretch or squash.
4. The dialog shows the resulting file size estimate. Adjust until you hit your target.
5. Click OK.
6. Save with Cmd+S to overwrite the original, or go to File → Export to save a copy in a different format or quality level.

Batch resize in Preview: Select multiple images in Finder, right-click → Open With → Preview. In Preview's sidebar, press Cmd+A to select all thumbnails. Then go to Tools → Adjust Size — Preview applies the same dimensions to every selected image in one pass.

Limitations: Preview lacks presets for common social media sizes. You type pixel values manually every time. It also does not support percentage-based resizing — you need exact dimensions. For preset-driven resizing or more control, use Pixotter or Automator.

Method 2: Pixotter in Your Browser

Pixotter's resize tool runs entirely in your browser via WebAssembly. Your photos never leave your Mac — no upload, no server, no account.

Steps:

1. Open pixotter.com/resize/ in Safari, Chrome, or Firefox.
2. Drop your photo onto the page (or click to browse).
3. Enter your target width and height. Toggle the lock icon to maintain the aspect ratio (recommended).
4. Click Resize.
5. Download the result.

Why use Pixotter over Preview: Pixotter processes photos locally just like Preview, but adds format conversion and compression in the same session. Resize a PNG, convert it to WebP, and compress it — one upload, one download. No switching between apps. It also handles batch resizing if you drop multiple files at once.

Method 3: Automator Quick Action (Batch Resize)

Automator lets you create a right-click menu item that resizes photos in bulk. Set it up once, use it forever.

Create the Quick Action (macOS Sonoma 14 / Sequoia 15):

1. Open Automator (search for it in Spotlight with Cmd+Space).
2. Click New Document → select Quick Action.
3. At the top, set Workflow receives current to image files in Finder.
4. In the left panel, search for Scale Images. Drag it into the workflow area on the right.
5. Automator asks if you want to add a Copy Finder Items step first (to preserve originals). Click Add — this saves copies before resizing, so you do not lose your full-resolution files.
6. In the Scale Images action, enter your target size in pixels (e.g., 1200). Choose whether the value applies to width or height by pixels.
7. Go to File → Save. Name it something clear like "Resize to 1200px".

Use the Quick Action:

1. Select one or more images in Finder.
2. Right-click → Quick Actions → Resize to 1200px.
3. The resized copies appear in the same folder.

Tips: Create multiple Quick Actions for different target sizes — "Resize to 800px" for blog images, "Resize to 1080px" for Instagram, "Resize to 600px" for email. Each one is a single right-click away.

Limitations: Automator does not show a preview before saving. It also uses a fixed size — you cannot enter custom dimensions per batch. For variable sizing, use Pixotter's batch tool or the sips command below.

Method 4: sips CLI (Built-in macOS Command)

sips (Scriptable Image Processing System) ships with every Mac. No install needed — open Terminal and go.

Resize a single photo to a specific width (aspect ratio preserved):

sips --resampleWidth 1200 photo.jpg --out resized-photo.jpg

Resize to a specific height:

sips --resampleHeight 800 photo.jpg --out resized-photo.jpg

Resize to exact dimensions (may distort if aspect ratio differs):

sips -z 800 1200 photo.jpg --out resized-photo.jpg

The -z flag takes height first, then width. This forces exact dimensions — use it only when you know the target matches your photo's aspect ratio, or when distortion is acceptable.

Batch resize all JPEGs in a folder:

mkdir resized
for f in *.jpg; do
  sips --resampleWidth 1200 "$f" --out "resized/$f"
done

Check current dimensions before resizing:

sips -g pixelWidth -g pixelHeight photo.jpg

sips is fast, scriptable, and requires zero setup. If you are comfortable in Terminal, it is the most efficient way to resize photos on Mac. For more command-line image processing, see our batch resize images guide.

Method 5: ImageMagick 7.1.x via Homebrew

ImageMagick gives you fine-grained control over resampling algorithms, output quality, and format conversion — overkill for one photo, but essential for production pipelines and automated workflows.

Install:

# Install Homebrew if you do not have it
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

# Install ImageMagick
brew install imagemagick

# Verify
magick --version
# ImageMagick 7.1.x

Resize to a specific width (aspect ratio preserved):

magick input.jpg -resize 1200x output.jpg

Resize to exact dimensions (ignoring aspect ratio):

magick input.jpg -resize 1200x800! output.jpg

Resize only if the image is larger (no upscaling):

magick input.jpg -resize '1200x>' output.jpg

The > flag means "shrink to fit, never enlarge." This is the safest option for mixed-size batches.

Batch resize with quality control:

mkdir resized
for f in *.jpg; do
  magick "$f" -filter Lanczos -resize 1200x -quality 85 "resized/$f"
done

The -filter Lanczos flag uses the same sharp resampling algorithm that Preview uses. The -quality 85 flag controls JPEG compression — 85 is a strong default that balances file size and visual quality. For more on balancing file size and quality, read our resize without losing quality guide.

Common Resize Dimensions

Keep this table handy. These are the dimensions you will reach for most often when resizing photos on Mac.

Social Media

Web and Email

For a complete dimension reference including print sizes, see the full resize guide.

Batch Resize on Mac: Which Method to Pick

All five methods handle batch resizing, but they differ in setup effort, flexibility, and speed.

For most people: Preview or Pixotter. Preview is already on your Mac; Pixotter adds format conversion and compression in the same step.

For developers: sips for quick jobs, ImageMagick for pipelines that need algorithm control. Both pair well with cron jobs and shell scripts.

For recurring workflows: Automator. The right-click integration makes it the fastest option once set up.

For a deeper comparison of batch resize methods across platforms, read our batch resize images guide.

FAQ

Does resizing a photo on Mac reduce the file size?

Yes. A 4000 x 3000 photo (12 million pixels) resized to 1200 x 900 (1.08 million pixels) drops by roughly 90% in pixel data. File size decreases proportionally. If you need to shrink file size without changing dimensions, compress the image instead. Our compress images on Mac guide covers native macOS compression methods in detail.

How do I resize a photo on Mac without losing quality?

Downscaling is nearly lossless — you are averaging existing pixel data, and the result often looks sharper at display size. Use Lanczos resampling (Preview and ImageMagick use it by default) for the sharpest output. Save to a lossless format like PNG if every pixel matters. The full technical breakdown is in our resize without losing quality guide.

Can I resize a photo on Mac using only the keyboard?

Almost. Open the photo in Preview, press Cmd+Option+I to open the Adjust Size dialog, type your dimensions, press Return to confirm, then Cmd+S to save. The only mouse interaction is selecting the file in Finder — though you can do that with arrow keys and Return too.

What is the difference between resizing and cropping on Mac?

Resizing scales the entire image to new dimensions — every part of the photo gets smaller or larger. Cropping removes the edges and keeps a portion at the original resolution. Use resize when the photo is too large for its destination. Use crop when you need to remove unwanted areas or change the composition. Our crop image on Mac guide covers five cropping methods.

How do I resize a photo for email on Mac?

Resize to 600 pixels wide — this is the rendering limit for Gmail and Outlook. In Preview: Tools → Adjust Size, enter 600 in the Width field, click OK, then File → Export as JPEG at 70-80% quality. Target file size: under 100 KB. You can also use Pixotter's compression tool to hit a specific file size target after resizing.

Does Preview preserve EXIF data when resizing?

Yes. Preview keeps all metadata (camera model, date, GPS coordinates) intact when you resize and save. If you want to strip metadata for privacy, use ImageMagick with the -strip flag: magick input.jpg -resize 1200x -strip output.jpg. For more on metadata, see our remove EXIF data guide.

How do I resize multiple photos to different sizes on Mac?

Preview and Automator apply the same dimensions to every photo in a batch. For per-photo sizing, use Pixotter — drop multiple photos, set individual dimensions for each, and download them all. Alternatively, write a sips or ImageMagick shell script that reads target dimensions from a CSV or filename pattern.

Can I undo a resize in Preview?

If you saved with Cmd+S (overwriting the original), you can undo only while Preview is still open — press Cmd+Z and then save again. Once Preview closes, the change is permanent. To be safe, always use File → Export to save a resized copy and keep the original untouched.