what is a png file? everything you need to know

what png stands for

png stands for portable network graphics. it was developed in the mid-1990s as a free, open replacement for the gif format, which had patent issues at the time. the name "portable" refers to the fact that png files look the same on any device or operating system, which wasn't guaranteed with earlier formats.

png became a web standard and has been the go-to format for graphics, logos, and images requiring transparency ever since.

the defining feature: lossless compression

the most important thing to understand about png is that it uses lossless compression. this means when you save an image as png, every single pixel is preserved exactly. nothing is discarded. when you open the file again, it's bit-for-bit identical to the original.

this is very different from jpg, which uses lossy compression. jpg achieves smaller file sizes by permanently discarding some image data, based on what the human eye is unlikely to notice. the trade-off is that the saved file is never quite the same as the original, even if the difference is invisible at normal viewing.

for png, there's no trade-off. the compression it uses makes files smaller without throwing anything away. the catch is that lossless compression can only reduce file sizes so much, which is why png files are often larger than jpg files of the same image.

transparency: the other big thing

png supports full transparency, including partial transparency. in technical terms, this is called an alpha channel. every pixel in a png can have its own level of opacity from completely transparent to fully opaque, with every gradation in between.

this is why png is the standard format for logos, icons, and cutout images. when you see a company logo on a website that seamlessly blends into any background color, it's almost certainly a png with a transparent background.

jpg has no transparency support at all. webp does support transparency, which is one of the reasons it's considered a modern upgrade for many png use cases. but png's transparency support is mature, universally supported, and well understood.

when png is the right choice

when png is NOT the right choice

photographs. lossless compression doesn't work as efficiently on photographs as it does on simpler graphics. a png photograph will often be 3-5x larger than the equivalent jpg or webp at comparable quality. for photos going on a website or being shared online, jpg or webp are much better choices.

large website images. if file size and page speed matter, png is rarely optimal for anything other than graphics and logos. the right format for web images depends on the content type, but png is almost never the right choice for photographs or large hero images.

if you're finding your png files are too large to share or too slow to load, converting to jpg or webp is usually the answer.

png vs jpg: the quick version

converting png to other formats

if you have a png file that's too large, or you need it in a different format, converting is straightforward. the main things to consider are whether your image uses transparency (which limits your options to webp or keeping it png) and whether it's a photograph or a graphic.

cozyconvert lets you convert png to jpg, webp, bmp and more, entirely in your browser. your files never leave your device, which matters when you're converting personal photos or confidential graphics.