How to Batch Convert Images on Mac (No Apps Needed)

Converting fifty images one at a time is a job for a computer, and your Mac already knows how. Preview exports whole batches, Finder's Quick Action converts on right-click, and sips in Terminal handles the truly enormous jobs. No downloads, no watermarks.

Preview: Export Selected Images

1. Select all the images in Finder and open them with Preview (press Cmd+O or right-click → Open With → Preview). They open as one window with a thumbnail sidebar.
2. Click in the sidebar and press Cmd+A to select every image.
3. Choose File → Export Selected Images…
4. Click the Options button in the save dialog and choose the output format — JPEG, PNG, HEIF, or TIFF (and a quality slider for JPEG).
5. Pick a destination folder and click Choose.

Preview writes converted copies into that folder and leaves your originals alone. Tip: export into a fresh folder so the new files are easy to find (and easy to delete if you picked the wrong settings).

Finder: the Convert Image Quick Action

Even faster for common cases — no app window at all:

1. Select the images in Finder.
2. Right-click → Quick Actions → Convert Image.
3. Choose format (JPEG, PNG, or HEIF) and size — Actual Size keeps dimensions, or downsize the whole batch to Small/Medium/Large in the same pass.
4. Click Convert.

Copies appear beside the originals. This is the only built-in route that converts and resizes in a single step — shrinking a batch of 12 MB photos to email-friendly copies is exactly what the Small and Medium size options are for.

Terminal: sips for power users

For hundreds of files, scripts, or repeatable jobs, use sips (scriptable image processing system), which ships with macOS:

# convert every HEIC in the current folder to JPEG, into a new "jpg" folder
mkdir jpg
sips -s format jpeg -s formatOptions 85 *.heic --out jpg

# undo: your originals were never touched — just remove the output
rm -r jpg

-s formatOptions 85 sets JPEG quality (0–100). Swap jpeg for png, tiff, or heic to go the other way, and change *.heic to match your source files. Because sips --out writes to a separate folder, the worst-case failure is an empty folder — your source images are never modified.

sips can also resize in the same pass. Add -Z 1600 to cap the longest edge at 1600 pixels while keeping the aspect ratio:

# convert to JPEG and shrink to max 1600px in one command
sips -s format jpeg -Z 1600 *.png --out jpg

Picking the right tool

• A dozen photos for an email: Finder Quick Action — three clicks, done.
• Mixed formats, care about JPEG quality: Preview, because the Options pane gives you the quality slider.
• Hundreds of files, or the same job every week: sips, which you can drop into a shell script or an Automator Quick Action so it runs from the right-click menu.

Whichever you pick, all three share the same safety property: they write new files rather than touching originals. The only cleanup you'll ever need is deleting a folder of copies.

Also worth knowing

If your batch is mostly iPhone photos, the HEIC-specific options — including stripping location metadata before you share, and stopping your iPhone from shooting HEIC in the first place — are covered in how to convert HEIC to JPG on Mac. And if the files just need to be smaller rather than a different format, resizing the batch is often the better fix than recompressing it.