Short version: photos go in JPG, logos and screenshots go in PNG, and anything headed for a website is usually smallest as WebP. The longer version explains why, which helps on the days the short version gives you a 9 MB file.
JPG: built for photographs
JPG compression dates from 1992 and works by discarding detail the eye is least likely to miss. On a photo of a beach that’s a great trade: a tenth of the size, no visible change. On a screenshot with small black text it’s a poor one, because the method smears hard edges and leaves grey speckles around letters.
Two more limits. JPG has no transparency, so a cut-out saved as JPG gets a solid background. And every re-save compresses again, so a picture edited and saved ten times looks worse than one saved once.
PNG: exact pixels and see-through backgrounds
PNG is lossless. What you save is what you get back, pixel for pixel, and it can make parts of the image transparent. That makes it right for logos, icons, diagrams, screenshots and anything you’ll edit again.
The cost shows up with photos. A 12-megapixel photo that’s 3 MB as JPG can be 15 MB or more as PNG, with nothing to show for it on screen. If someone sends you a huge PNG photo, PNG to JPG is the fix.
WebP: the smaller file for websites
Google released WebP in 2010. It does both jobs: a lossy mode for photos and a lossless mode with transparency. Google’s own tests put lossy WebP 25 to 34% smaller than JPG at matching quality, and every current browser has displayed it since Safari added support in 2020.
The weak spot is outside the browser. Some older desktop programs, print services and upload forms still refuse WebP. So it’s a delivery format: keep your original, and make a WebP copy with JPG to WebP for the page.
A quick way to choose
- Camera photo to email or print: JPG.
- Logo, icon, screenshot, or anything with a transparent background: PNG.
- Any image on a web page where speed matters: WebP, with the original kept safe.
- A form or a printer that names a format: whatever it names.
Got the wrong one? Image Converter switches between all of these. And if the format is right but the file is still heavy, Compress Image shows the new size before you save.
What about AVIF and GIF?
AVIF is newer and often smaller than WebP, but slower to create and less widely accepted by apps. GIF is only worth using for short animations, and even there a small MP4 is usually a fraction of the size.
Common questions
Does converting JPG to PNG improve quality?
No. Detail that JPG removed is gone. The PNG is just a bigger file of the same picture.
Which format is best for Instagram or Facebook?
Upload a good JPG. Both sites re-compress whatever you send, so a huge PNG gains nothing.
Is WebP safe to use on my website?
Yes for visitors: all current browsers show it. Keep JPG or PNG originals for anything outside the browser.