Zipnify Fast image tools. Zero uploads.PNG vs JPG: when to use each image format
Almost everyone has saved an image and wondered whether to pick PNG or JPG. The right answer depends on what the image contains and what you will use it for. Choosing well saves space, avoids blurry edges and makes your files look professional.
How JPG works
JPG, also written JPEG, was designed in the nineties for photographs. It splits the image into small blocks and discards colour and detail information the eye barely perceives. That is why it produces very light files, but every time it is saved again it loses a little more quality. It does not support transparency: if your image has a transparent background, converting to JPG fills it in, normally with white.
Its great strength is the ratio of weight to appearance in images with smooth gradients and thousands of colours, such as landscapes, portraits or product photos.
How PNG works
PNG uses lossless compression: the image is stored exactly as it is, without degrading no matter how many times you open and save it again. It also supports transparency with partial levels, which allows soft shadows and clean edges over any background.
Its drawback is weight. With photographs, a PNG can be three to six times larger than an equivalent JPG. With images made of a few flat colours, such as logos, icons, diagrams or screenshots with text, it can even be lighter than JPG and much sharper.
A simple rule to decide
If it is a photograph, use JPG, or better WebP if the destination supports it. If it is a graphic with flat colours, text, thin lines or you need transparency, use PNG. If you will keep editing the image several times, work in PNG and export to JPG only at the end.
An everyday example: the photo of your product for an online shop goes in JPG; your business logo, which is placed over backgrounds of different colours, goes in PNG; the screenshot of an error you send to support goes in PNG because the text reads better.
Weight differences: an example
Imagine a photograph of 1920 by 1280 pixels. As a JPG at quality 80 it may weigh around 300 to 500 KB. The same image as a PNG easily exceeds 2 MB. Now take a logo of 800 by 300 pixels with four colours: as a PNG it may weigh 10 KB, and as a JPG about the same but with slightly dirty edges around the text.
Exact numbers vary with each image, but the trend repeats: the right format for the right content produces smaller files that look better.
What about WebP
WebP is a modern format that supports lossy and lossless compression, plus transparency. For photographs it usually weighs less than JPG with comparable appearance, and for graphics it can replace PNG. Today every current browser recognises it, which makes it an excellent option for websites.
Its limit is compatibility with old software and some portals that only accept JPG or PNG. If a form rejects your file, convert it to the format it asks for.
How to convert between formats safely
To go from PNG to JPG, use the Zipnify conversion tool, choose the quality and download the result. If the image had transparency, it will be filled with a background colour. Going from JPG to PNG does not improve quality; it only stops further loss in future saves, and the file will be heavier.
Remember that conversion happens in your browser, without uploading your files. Always keep the original in case you need to export again with different settings.
Frequently asked questions
Does PNG have better quality than JPG?
PNG loses no information when saved, but that only matters for graphics and screenshots. For photographs, a well-configured JPG looks the same at much lower weight.
Why is my PNG so heavy?
It is probably a photograph. PNG stores every detail without discarding anything, and photos have a huge amount of detail. Convert it to JPG or WebP.
Does JPG support a transparent background?
No. When you convert an image with transparency to JPG, the background is filled, normally with white.
Should I convert a JPG to PNG to improve it?
It does not improve the image. It only prevents further loss in future saves and increases the file weight.