I have these
.jpg pics and I removed their background. But after I saved them to
.png their file sizes skyrocketed. Like a
198kb file becomes
3.82mb after I save it to
.png. Why is that?
JPG uses much worse compression settings (worse for quality, better for size)
When you save a photo as a
.jpg it's heavily compressed (and blurred out too) which is why you have a much smaller file size.
See this excellent answer by Vincent on this. Also have a look at the main question and other answers, great info!
There's also an awesome post on Stack Overflow about this.