The PNG image format

What it is

PNG (Portable Network Graphics) was developed in the mid-1990s as an open, patent-free alternative to GIF, and it became a W3C recommendation and later an international standard. Today it is supported by every browser, operating system and image editor.

PNG uses lossless compression. Every pixel is stored exactly, so opening and saving a PNG any number of times never changes the image. The compression works by finding repeating patterns. Images with large areas of the same color, such as screenshots and logos, compress very well. Photos, where almost every pixel differs slightly from its neighbors, do not.

PNG can store images in several ways: an indexed palette of up to 256 colors, full color with 8 bits per channel, and even 16 bits per channel for special uses, each with or without transparency.

Strengths

• Lossless. No compression artifacts, no quality loss between saves.
• Transparency. A full alpha channel allows soft, semi-transparent edges on logos, icons and cutouts.
• Sharp text and lines. Screenshots, diagrams and interface graphics stay crisp.
• Universal support. PNG works everywhere JPG does.

Weaknesses

• Large photos. A photo saved as PNG is often several times larger than a good JPG, with no visible benefit.
• No real gain from JPG sources. Converting a JPG to PNG cannot restore lost detail.
• Animation is rarely used. An animated extension, APNG, exists and works in current browsers, but most PNG files are still images.

When to use it

Use PNG for screenshots, logos, icons, charts, illustrations with flat colors, and any image that needs transparency. It is also a good working format when you will edit an image several times. For photos, JPG or WebP is almost always the better choice. The PNG vs JPG guide compares them in detail.

How to open and convert PNG

PNG files open in every browser and image viewer. These tools cover the common conversions:

• PNG to JPG: the PNG to JPG converter makes photo PNGs much lighter. Transparent areas are filled with a background color you choose, white by default.
• PNG to WebP: the WebP converter creates smaller website images and keeps transparency.
• PNG to AVIF: the AVIF converter for the smallest modern files.
• PNG to ICO: the PNG to ICO converter creates Windows and website icons.
• PNG to PDF: the image to PDF tool puts images onto PDF pages.
• Smaller PNG: the PNG compressor reduces colors to a palette of 256 or fewer and keeps transparency. It works best for screenshots, logos and illustrations.

The tools run in your browser, so files stay on your device.