Because JPG and PNG image formats should be used for different purposes:
Because, this Online JPG to PNG Converter is ease-to-use, fast, free and all you have to do to convert JPG to PNG is select the image and click button "Convert To PNG".
TIP: After conversion check file size. If new PNG has file size bigger than original JPG, use JPG! Why? Because it means that original JPG is better format for your image file.