The Difference Between PNG8, PNG24, and PNG32
How to choose the right PNG format when saving your images.
Edited: 2026-02-13 13:45
The terms PNG8, PNG24, and PNG32 are commonly used by image editors to describe different bit depths when exporting PNG files. Technically, they are not separate file formats, but shorthand descriptions of how color and transparency data are stored inside the PNG file.
PNG8 uses indexed color, meaning the image is limited to a palette of up to 256 colors (8 bits). PNG24 uses truecolor, storing 24 bits per pixel (8 bits per red, green, and blue channel). PNG32 stores the same 24-bit color data, but adds an additional 8-bit alpha channel, resulting in 32 bits per pixel.
The additional alpha channel in PNG32 enables full per-pixel transparency. This is different from the simpler transparency available in PNG8, where individual palette entries can be either fully opaque or fully transparent.
Choosing between PNG8, PNG24 and PNG32
The right choice depends on the content of your image and whether transparency is required.
- PNG8 is ideal for logos, icons, UI elements, and graphics with few colors. Smaller palettes usually result in significantly smaller file sizes.
- PNG24 is suitable for detailed images that require full color but no transparency.
- PNG32 is necessary when you need smooth alpha transparency, such as shadows, glows, soft edges, or transparent gradients.
Using the lowest practical color depth is one of the most effective ways to reduce file size for web use. Fewer colors generally compress better because the PNG format uses lossless DEFLATE compression, which benefits from repeated patterns and limited variation.
Be aware that PNG32 files can grow large quickly due to the added alpha channel. While the visual flexibility is powerful, it comes at a cost in file size.
Savings and optimization
PNG is a lossless format, meaning image quality does not degrade from compression. However, file sizes can still be reduced by optimizing metadata, palette usage, and compression parameters.
Most modern image editors provide built-in “Save for Web” functionality, but further size reductions can often be achieved using free and open source tools such as PNGOUT and OptiPNG. These tools recompress the image without altering visual quality.
There is generally no need to pay for PNG conversion or optimization software. PNG is an open standard, and high-quality open source tools are widely available. For an open format, accessibility and free tooling should be the norm.
For editing, Paint.net and GIMP both perform well and offer solid export controls for minimizing file sizes for web use.
A note on modern formats
While PNG remains excellent for logos, UI graphics, and images requiring lossless quality or transparency, newer formats such as WebP and AVIF can offer dramatically smaller file sizes for photographic content. PNG still has its place — particularly where compatibility, sharp edges, and predictable rendering are important.
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