How to Batch Resize Images on Mac With Preview

You’ve got 60 photos coming in at 5000 pixels wide and you need them at 1200 for a website. Or 30 product images all need to be exactly 1080x1080 squares for a marketplace listing. The web is full of paid apps for batch image resizing, and almost none of them do anything that Preview — the built-in macOS image viewer — can’t do for free.

Here’s how to batch resize images using Preview, plus when it’s not the right tool.

Preview can batch process images

Preview is more capable than its plain UI suggests. When you open multiple images at once, you can apply changes to all of them in one go. Resize, format conversion, rotation, even basic cropping — all built in.

To batch open: select multiple images in Finder, right-click → Open With → Preview. Or Cmd+Click to select images one at a time, then Cmd+O from Preview’s menu.

In Preview, the sidebar (View → Thumbnails or Option+Cmd+2) shows every image you opened. Select all in the sidebar with Cmd+A. Now any tool you use applies to every selected image.

Batch resize to a specific dimension

With all thumbnails selected:

1. Tools menu → Adjust Size
2. The dialog has fields for Width, Height, and Resolution
3. Make sure “Scale proportionally” is checked (so aspect ratios stay correct)
4. Make sure “Resample image” is checked (otherwise nothing actually changes)
5. Set Width or Height — the other dimension auto-fills
6. Click OK

Every selected image gets resized in place. The thumbnails update to show the new sizes.

To save: File → Save (or Cmd+S) saves all changed images. Each is overwritten with the resized version.

If you want to keep originals, duplicate the images first or set up a separate folder.

Batch resize by percentage

Same Adjust Size dialog, but pick “percent” from the dropdown next to Width. Set Width to 50 and the images shrink to 50% of their current size.

Useful when you don’t care about exact pixel dimensions but just need things smaller. “Make all these 25% the size they are now” is one operation.

Batch convert formats

If you’ve got 40 PNG files and need them as JPGs:

1. Open all in Preview
2. Cmd+A in the sidebar to select all
3. File → Export Selected Images
4. A save dialog appears with a Format dropdown — pick JPEG, PNG, TIFF, HEIC, PDF, or several others
5. Pick a destination folder
6. Click Choose

Every selected image exports to the new format. Originals stay untouched.

Quality slider is available for JPEG. Drag higher for less compression and bigger files; lower for smaller files at the cost of artifacts.

For HEIC → JPEG conversion (common when shipping iPhone photos to people who can’t open HEIC), this is the fastest way to do it on Mac. Open the HEIC files in Preview, select all, Export, pick JPEG, done.

Batch rotate

Some camera and phone images come in rotated wrong. Preview can fix in bulk:

1. Open all images
2. Sidebar → Cmd+A
3. Tools → Rotate Left or Rotate Right (Cmd+L or Cmd+R)

Every selected image rotates 90 degrees. Run twice for 180. Save when done.

For mixed rotations (some right, some wrong), don’t bulk select — fix them individually. But for a folder of consistently wrong-rotated photos, bulk rotation saves a lot of clicks.

Set a fit-within size for the web

The most common batch-resize use case is “fit images to be no larger than 1200 pixels on the longest side, for a website.” Preview handles this elegantly.

1. Open all images
2. Sidebar Cmd+A
3. Tools → Adjust Size
4. Pick “Fit into” from the dropdown next to Width
5. Choose a preset (640 x 480, 800 x 600, 1024 x 768, 1280 x 1024, 1920 x 1200) or pick Custom and enter your own
6. With “Scale proportionally” on, every image gets resized so its longest side fits within the limit, with aspect ratios preserved

This is the “shrink everything for the web” workflow. Run it on a folder of photos, save, and you’ve got web-friendly versions in seconds.

Reduce file size without changing dimensions

If you don’t want to resize but just compress, use Export instead of Save:

1. Open the image
2. File → Export
3. Format: JPEG (or HEIF for smaller files at similar quality on modern Macs)
4. Drag the Quality slider to a lower setting
5. Watch the file-size estimate update
6. Save to a new location to preserve the original

For batch quality reduction, use Export Selected Images on a multi-image selection.

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Batch crop or annotate

Cropping in Preview is per-image only — there’s no “crop all selected to the same area.” Same with annotations. For these, Preview is a one-image-at-a-time tool.

If you need batch cropping (every image cropped to identical dimensions or center-cropped to square), the right tools are:

• Automator — set up a workflow with the Crop Images action
• sips — Terminal command for batch image work
• Affinity Photo — full image editor with batch processing
• ImageMagick — Terminal-based image processor, very flexible

For straightforward batch crop-to-square:

cd ~/Pictures/MyImages
mkdir cropped
for img in *.jpg; do
  sips --cropToHeightWidth 1080 1080 "$img" --out "cropped/$img"
done

The sips command is built into macOS — no installation needed.

Use Automator to create a Quick Action

For repeatable batch operations, save them as a Quick Action via Automator:

1. Open Automator → New Document → Quick Action
2. “Workflow receives current” → image files in Finder
3. Drag in actions: “Scale Images” (set max size), “Change Type of Images” (convert format), or others
4. File → Save → name it “Resize for Web”

Now in Finder, right-click any image or selection → Quick Actions → “Resize for Web.” The workflow runs without opening Preview.

For repeated work this is faster than the manual Preview flow. You can chain multiple actions — “scale to 1200, convert to JPEG, save in a Resized subfolder” — into one click.

When Preview isn’t enough

Skip Preview when:

• You need precise per-image cropping — Preview’s batch tools don’t support this
• You need a watermark applied to all images — Automator or a dedicated tool
• You’re processing thousands of images — Preview gets slow with 500+ images open
• You need EXIF data preserved precisely — some Preview operations strip metadata

For those cases, look at:

• Photos app for non-destructive editing of your photo library
• Affinity Photo or Pixelmator Pro for full editing
• ImageOptim for compression-only batch work
• sips in Terminal for scriptable workflows

A typical web-image workflow

For images going to a website or blog post:

1. Drop original images into a folder, e.g., ~/Pictures/BlogPost-2026-04
2. Duplicate the folder (Cmd+D on the folder) to preserve originals
3. Open all images in the duplicate folder via Preview
4. Tools → Adjust Size → Fit into 1600 x 1200
5. Cmd+A to select all in sidebar, then Save (Cmd+S)
6. File → Export Selected Images → JPEG, quality around 80%
7. Upload from the duplicate folder

End to end: about 90 seconds for 50 images. Plus you’ve got originals safe in case you need them later.

Don’t forget rotation metadata

Some images carry rotation in EXIF metadata rather than actually being rotated. They look right in Preview and Photos but might appear sideways elsewhere.

To bake rotation into the file:

1. Open the image in Preview
2. Tools → Rotate (any direction, then back if needed)
3. Save

This forces Preview to write the actual rotated pixels, removing reliance on EXIF orientation. Useful for images going to web platforms that don’t honor EXIF correctly.

Preview is one of those Mac apps that does much more than its name suggests. For 90% of batch image work — resize, format convert, rotate, compress — it’s all you need. Skip the App Store image apps and use what’s already on your Mac.