PNG (Portable Network Graphics)
The web's go-to format for sharp, transparent images that never lose a single pixel.
| Full name | Portable Network Graphics |
| Extension | .png |
| MIME type | image/png |
| Developer | PNG Development Group (led by Thomas Boutell), standardized by W3C and ISO |
| Released | 1996 (W3C Recommendation, 1 October 1996) |
| Type | Raster image |
| Compression | Lossless (DEFLATE) |
| Color depth | Up to 48-bit RGB or 64-bit RGBA |
What is a PNG file?
PNG is a lossless raster image format built for the web. It stores every pixel exactly as saved, so images never degrade no matter how many times you open or re-save them. It supports full transparency through an alpha channel, making it the standard choice for logos, icons, and graphics that need to sit on any background.
PNG stores image data as a grid of pixels, each with color values and an optional transparency level. The format uses DEFLATE compression, the same algorithm behind ZIP files, combined with predictive filtering to shrink file sizes without discarding any information. Color modes include grayscale, indexed color (palette-based), and full truecolor, with or without an alpha channel. Bit depth can range from 1 bit per channel up to 16 bits per channel.
History
PNG was created in 1995 by an internet working group led by Thomas Boutell as a patent-free replacement for GIF. The GIF format was encumbered by Unisys patents on the LZW compression algorithm, which pushed the web community to build an open alternative. PNG 1.0 became a W3C Recommendation on 1 October 1996, and the specification was later adopted as the ISO/IEC 15948:2003 international standard.
How it works
A PNG file starts with an 8-byte signature that identifies it as PNG. After that, the file is made up of chunks, each containing a length field, a 4-byte type code, a data payload, and a CRC-32 checksum for error detection. The IHDR chunk must come first and stores the image dimensions, bit depth, color type, and interlacing method. Image pixel data lives in one or more consecutive IDAT chunks, and the file always ends with an IEND chunk.
What it is used for
- Logos and brand graphics that require a transparent background
- Screenshots and UI mockups where text sharpness matters
- Icons and web graphics at small sizes where detail must be preserved
- Source artwork files before converting to formats like WebP or JPEG
How to open it
Every major image viewer and browser can open PNG files without any extra software, including Windows Photos, macOS Preview, GIMP, Photoshop, and all modern web browsers. Online converters and tools like this site let you convert PNG to other formats directly in your browser.
Pros and cons
Strengths
- Lossless compression keeps image quality perfect through repeated saves
- Full alpha channel support allows smooth, partial transparency
- Wide support in every browser, operating system, and image editor
- Open standard with no patent restrictions
Trade-offs
- File sizes are larger than JPEG for photographs and complex scenes
- No native support for animation (that is the role of APNG or GIF)
- Not ideal for print workflows, which typically prefer TIFF or PDF
- 16-bit per channel support is not always honored by older software
Convert PNG files
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From PNG
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PNG FAQ
Is PNG or JPEG better for photos?
JPEG is usually better for photos. JPEG's lossy compression produces much smaller files for photographic content, where the slight quality loss is rarely visible. PNG is the better pick when you need pixel-perfect quality or a transparent background.
Does PNG support transparency?
Yes. PNG has a full alpha channel, which means each pixel can have its own opacity level from fully transparent to fully opaque. This makes it the standard format for logos, icons, and cut-out images on the web.
What is the difference between PNG and PNG-8?
PNG-8 uses an indexed color palette of up to 256 colors, similar to GIF, resulting in smaller files for simple graphics. Standard PNG (often called PNG-24 or PNG-32) stores full truecolor with millions of colors and is the right choice for anything with gradients or photographic detail.
Can I convert PNG to other formats without losing quality?
Converting PNG to another lossless format like WebP or TIFF preserves all image data. Converting to a lossy format like JPEG will introduce some quality reduction, but PNG itself will not degrade because it is lossless.