You’ve probably seen it a million times. You take a screenshot or download a high-res asset, and suddenly your desktop is cluttered with massive files ending in .png. It’s frustrating. These files are beautiful, sure, but they’re absolute storage hogs. If you’re trying to upload a profile picture or email a document, a PNG is often overkill. Honestly, you just need a JPG. Most people think they need to download some sketchy "free" converter from the App Store that’s probably just tracking their data. You don't. macOS has everything you need baked right into the system, though Apple hides the best features in plain sight.
The Preview method: The old reliable for how to convert from png to jpg on mac
Preview is the Swiss Army knife of macOS that nobody actually talks about. It’s the default app for opening images, but most people just use it to look at a photo and then close it immediately. That’s a mistake.
Open your PNG in Preview. Go up to the File menu and look for Export. Don't click "Export as PDF"—just "Export." A little dialogue box pops up. This is where the magic happens. You’ll see a dropdown menu labeled Format. Switch that from PNG to JPEG.
Now, here is the nuance most "how-to" guides miss: the Quality slider. PNGs are "lossless," meaning they keep every single pixel perfect. JPEGs are "lossy." When you slide that bar to the left, you're telling the computer to start guessing which pixels aren't important. If you’re just posting to Slack or Discord, 70% quality is usually plenty. You save a ton of space and nobody can tell the difference unless they're zooming in 400% to count the artifacts.
Using Quick Actions for bulk conversions
If you have fifty images, opening them one by one in Preview is a nightmare. It’s tedious. It’s a waste of a Saturday.
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Apple introduced something called Quick Actions in macOS Mojave, and it’s still the fastest way to handle how to convert from png to jpg on mac without actually opening an app. Highlight all your images in Finder. Right-click (or Control-click) them. Look for the "Quick Actions" submenu at the bottom.
Select Convert Image.
A small window appears. You can choose JPEG, keep the original metadata (like the date the photo was taken), and even decide if you want to keep the original file size or shrink it down to "Small," "Medium," or "Large." This is a lifesaver for web developers or anyone managing a blog who needs their site to load in under two seconds. It’s fast. It’s native. It’s basically magic.
The secret "Sips" command for terminal nerds
Sometimes the GUI (Graphical User Interface) is just too slow. Maybe you’re feeling a bit like a hacker today. macOS has a built-in command-line tool called sips (Scriptable Image Processing System). It’s been around for decades.
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Open Terminal. Type this: sips -s format jpeg input.png --out output.jpg.
It happens instantly. There’s no loading bar. No "Processing..." spinning wheel. It just does it. If you have a whole folder, you can use a wildcard like sips -s format jpeg *.png. Just be careful. The Terminal doesn't have an "undo" button. If you overwrite your only copy of a precious family photo, it’s gone. Always work on copies.
Why does this even matter? PNG vs. JPG explained
Why are we even doing this? Basically, it comes down to transparency and compression. PNGs support transparent backgrounds. If you have a logo that needs to sit on top of a colored website, you need that PNG. JPGs don't do transparency. If you convert a transparent PNG to a JPG, that clear background usually turns into a solid white or black block.
But for photos? JPG is king. A photo of your cat as a PNG might be 15MB. The same photo as a JPG might be 1.2MB. When you're paying for iCloud storage or trying to stay under a 20MB email limit, those megabytes matter. Professional photographers often use HEIC now (Apple’s newer format), but the world still runs on JPG. It's the universal language of the internet.
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Using the Photos app for the "Hidden" conversion
A lot of people manage their entire lives inside the Photos app. If you’ve imported PNGs there, you don’t need to drag them to the desktop to convert them. Just select the image in your library. Go to File > Export > Export 1 Photo.
Again, you’ll get the option to change the Photo Kind to JPEG. The Photos app actually gives you more granular control over the color profile (like sRGB), which is super helpful if you’re worried about the colors looking "off" when you upload them to Instagram or a professional printing service.
The AppleScript/Automator route for power users
If you find yourself doing this every single day, you should build a "Folder Action." You can set up a folder on your desktop called "Drop to Convert." Using the Automator app (which is in your Applications folder), you can create a script that says "Whenever a file is dropped here, change the type to JPG and move it to the trash."
It sounds complicated. It’s really not. You just drag a few blocks together like Legos. Once it’s set up, you never have to think about how to convert from png to jpg on mac ever again. You just toss files into a folder and they come out the other side smaller and ready to use.
Actionable Next Steps
- Audit your Desktop: Command-I (Get Info) on those big screenshots. If they are over 5MB, they’re prime candidates for conversion.
- Test the Quick Action: Select three random PNGs right now, right-click, and use the Convert Image tool. It’s the fastest habit to build.
- Check your Screenshots: By default, Mac saves screenshots as PNGs. If you want to change the default to JPG forever, open Terminal and type:
defaults write com.apple.screencapture type jpg; killall SystemUIServer. - Watch the Transparency: Before you batch convert, make sure you don't need those clear backgrounds. If you do, stick with PNG or try WebP if you're feeling adventurous.
The goal isn't just to change a file extension. It's to reclaim your storage and make your digital life move a little faster. You don't need third-party software for this. Your Mac is already powerful enough to handle it in seconds.