How to Convert Multiple Images on Mac: Preview, Quick Actions, sips and Batch Apps

How to convert multiple images on Mac: the quick answer

There are four practical ways to convert many images at once on a Mac. Finder's Convert Image Quick Action is the fastest for a selection of photos. Preview's Export Selected Images works for a few dozen files. Shortcuts and the sips command in Terminal can process a whole folder with fixed rules. A batch app such as Operimage, a free Mac app, handles very large folders, writes WebP and AVIF, and shows Before/After before you commit.

Whichever method you choose, the safe pattern is the same: write converted copies to a new folder, test a small sample first, and keep the originals. Converting to a lossy format such as JPEG never restores quality later, so the source files are your master copies. If you are still deciding on a target format, the hub on choosing and batch converting image formats compares JPEG, PNG, WebP, AVIF, HEIC and TIFF.

Method 1: Finder Quick Action (fastest for a selection)

Since macOS Monterey, Finder can convert images without opening any app. It is the quickest route when you have a selection of photos and need JPEG, PNG or HEIF copies right now. If you build node workflows today, the Retrobatch alternative comparison explains the trade-offs.

• Select: highlight the images in Finder (Command-A selects everything in a folder).
• Open the action: right-click the selection and choose Quick Actions → Convert Image.
• Choose format and size: JPEG, PNG or HEIF, at Small, Medium, Large or Actual Size.
• Metadata: tick or untick Preserve Metadata depending on whether the copies will be shared publicly.
• Result: converted copies appear next to the originals in the same folder, which can get messy in large folders.

Method 2: Preview's Export Selected Images

Preview converts several images in one pass if you open them together. Select the files in Finder and open them in Preview, click into the thumbnail sidebar, press Command-A to select every image, then choose File → Export Selected Images. Pick a destination folder, click Options, and choose the format. Preview writes JPEG, PNG, HEIC, TIFF, PDF and JPEG 2000.

Preview is excellent for a quick job, but it has clear limits for batch work. It cannot export WebP or AVIF, it does not remember settings between sessions, it flattens all files into one destination with no subfolder structure, and opening several hundred large photos at once can make it sluggish. There is also no side-by-side Before/After check across the batch; you only see results after export.

Method 3: Shortcuts or sips for scripted conversions

If the same conversion happens regularly, Shortcuts can automate it. A simple shortcut takes the selected Finder files, runs the Convert Image action (JPEG, PNG, HEIF, TIFF, GIF, BMP, PDF and more, with a quality setting) and saves the results to a chosen folder. You can enable it as a Quick Action so it appears in Finder's right-click menu.

Terminal users can use sips, the scriptable image tool built into macOS. To convert every HEIC in a folder to JPEG at 85% quality into a subfolder, run mkdir jpeg, then for f in *.HEIC; do sips -s format jpeg -s formatOptions 85 "$f" --out "jpeg/${f%.*}.jpg"; done. sips is fast and private, but it gives no preview, cannot write WebP or AVIF, and mistakes in a loop apply to every file, so test it on a copied folder first.

If your photos are still in the Photos app

Images that live in the Photos library are not ordinary files in a folder, so Finder and Preview cannot reach them directly. Select the photos in Photos, choose File → Export → Export Photos, and pick JPEG, TIFF or PNG, a size, and whether to include location information. Photos writes converted copies to the folder you choose and leaves the library untouched.

For large exports, a cleaner path is to export the unmodified originals first (File → Export → Export Unmodified Original), which gives you the HEIC files exactly as the iPhone captured them, then convert that folder in one batch with the format, quality and metadata rules you want. This also keeps edits and conversions separate, so you can redo the conversion later without exporting from Photos again.

Method 4: Convert a whole folder with a batch app

A dedicated batch converter is the better route when the folder is large, the sources are mixed, the destination needs WebP or AVIF, or the job will repeat. In Operimage, choose Convert in the sidebar and drag files onto the window or click Folder. The header confirms how many images are ready, and you can drop more or clear the list at any time.

Pick one of the nine output formats and set the quality slider; 82% is a good default for JPEG and WebP. Click any file in the image list to compare Before and After at full detail, and press Refresh after changing settings. When the sample looks right, click the round Convert button. Operimage writes new files rather than replacing originals, can keep the source folder structure, and Reveal output opens the result in Finder. Everything runs on the Mac, so nothing is uploaded.

Which method should you use?

Match the method to the size and frequency of the job. A dozen iPhone photos for an email: Finder Quick Action. Thirty screenshots to JPEG for a document: Preview. A nightly conversion on a server-like Mac: a Shortcut or sips script. A product shoot of 600 images to WebP with subfolders per product, or the same conversion every week: a batch app with saved settings.

The hidden cost of the built-in routes is repetition rather than speed. Each Preview export starts from scratch, each Quick Action run asks the same questions, and scripts need maintenance when a folder layout changes. If you convert similar folders more than once a month, saving the exact recipe once, then rerunning it, removes most of the decisions and most of the mistakes. That is the main reason teams and store owners move to a batch app, not raw conversion speed.

If you want to compare desktop converters in more depth, including Permute, Retrobatch and XnConvert, see the review of offline converter apps for Mac.

Keep folders and file names under control

Conversion itself is rarely what goes wrong in a big batch; the output organization is. When source images live in subfolders by client, product or date, keep that structure in the output so you do not end up with one flat folder of 2,000 files. When you merge folders, duplicate names such as IMG_0001.jpg can collide, so add a counter or folder name.

If the converted files need readable or SEO-friendly names, run a rename step after conversion. The guide to giving a whole folder of photos consistent names covers patterns, counters and sorting into folders, and Operimage's Rename tool shows a live preview of every new name before anything changes.

Convert and resize in the same run

Many conversions also need new dimensions: iPhone photos are 4032 × 3024 pixels, far larger than an email, a web page or a marketplace needs. Converting and then resizing in a separate app means two passes and two chances to lose names. Instead, resize after converting in the same session, or chain both steps in an Operimage Workflow such as convert → resize → compress, then rerun it on the next folder.

For web use, 2048 pixels on the long edge is a safe default; 1600 pixels is plenty for most blog images. The bulk resizing guide explains fit versus fill, aspect-ratio presets and why you should never upscale small images.

Common problems when converting many images

A few edge cases cause most failed batches. Include examples of each in your test subset.

• iPhone HEIC files: portrait photos rely on an orientation tag, and Live Photos contain a separate video that conversion drops. The HEIC to JPEG walkthrough covers both.
• Downloaded WebP images: many older apps cannot open them. See turning saved WebP images into JPEGs for settings that avoid quality loss.
• Transparency: PNG logos converted to JPEG get a solid background. Keep PNG, WebP or AVIF if you need transparency.
• Location data: converted copies may keep GPS coordinates. Follow the steps for stripping EXIF and GPS before sharing.
• Colors look flat: Display P3 photos can look duller if the color profile is dropped. Compare one output in Safari and Chrome.
• Files bigger than before: converting JPEG photos to PNG or TIFF increases size because those formats are lossless.