Convert Any Image to JPG on Mac, One or a Whole Folder

Preview handles PNG, HEIC, TIFF, WebP and most other formats macOS can open.

1. Open the image in Preview.
2. Choose File > Export (hold Option to see Export As).
3. Set Format to JPEG and drag the Quality slider.
4. Pick a name and click Save. The original stays where it is.

Preview shows the estimated file size as you move the slider, which makes it a decent tool for one picture. It converts one file at a time, though. To select several in Preview, open them together, select them in the sidebar, then choose File > Export Selected Images. That works for a handful, and it gets clumsy past that.

sips ships with macOS and converts a folder in one line. Make an output folder first, then loop over the files:

mkdir -p jpg-out
for f in *.png *.heic *.tiff; do
  sips -s format jpeg -s formatOptions 85 "$f" --out "jpg-out/${f%.*}.jpg"
done

The formatOptions value is JPEG quality from 0 to 100. Without --out, sips writes over the file you give it, so keep the output folder. Our sips guide has more patterns, including resizing in the same pass.

Two limits showed up in testing. A loop only sees the extensions you list, so a folder with a stray .webp or .JPEG gets skipped without a warning. And sips refused one BMP my test tools produced with “Cannot extract image from file”, so check the output count against the input count.

Yes. We converted five copies of one 1600 px photo, saved as PNG, TIFF, WebP, BMP and HEIC, in a single Smol convert job. All five came out as JPG, each as a new file beside its source with a _converted suffix. The same five went through a sips loop at quality 85.

Single run, one photo, so treat the sizes as an example and not a benchmark. Notice two things. A JPG can be much larger than a lossy source such as WebP or HEIC, because you are turning an already compressed picture into a different lossy one. And Smol’s convert produces a larger, higher-quality JPG than sips at 85. That is how Convert works: it ignores the quality setting.

Converting changes the container and keeps quality high. Shrinking is a separate step. In Smol, use Compress with the output format set to JPG, where the quality slider (default 75) does apply. Our image converter roundup compares the options, and the PNG to JPG guide and HEIC to JPG guide cover the two most common sources.

Remember what JPG cannot do. It has no transparency, so a transparent PNG gets a flat background. Each re-save loses detail, so convert from the original, not from a JPG of a JPG.

For a single image, or a short list of one format, Preview and sips are free and already installed. Use them. You do not need an app to turn one PNG into a JPG.

Smol earns its $29 (once, one Mac) when the folder is mixed, when you convert often, or when you want a Finder right-click instead of a script. Everything runs on your Mac and nothing is uploaded. It is not the fastest: sips finished our five files in a fraction of a second. If that matters more than convenience, stay with the shell. Details are on the buy page.