What is PNG? The Portable Network Graphics Format Explained

PNG is the format you reach for when quality cannot be compromised — when you need a logo without a white box behind it, a screenshot where every pixel stays crisp, or an icon that scales cleanly on any background. Understanding what a PNG file actually is, and when it beats the alternatives, saves you from using the wrong format and wondering why your images look blurry or bloated.

What is PNG?

PNG stands for Portable Network Graphics. It is a raster image format that uses lossless compression, meaning every pixel in the original image is preserved exactly when you save and re-open the file.

A Brief History

PNG was created in 1996 specifically to solve a legal problem. The GIF format (then the dominant web image format) relied on the LZW compression algorithm, which was patented by Unisys. Web developers faced the prospect of paying royalties just to display GIFs. A group of developers created PNG as a free, open alternative.

The name "PNG" is sometimes recursively described as "PNG's Not GIF" — a nod to the circumstances of its creation.

PNG became a W3C standard in 1996 and was extended in 2003. Every major browser, operating system, and image editor has supported it natively for decades.

Technical Specifications

• Compression: DEFLATE (lossless) — related to the zlib library
• Color depth: 1-bit (black/white) up to 48-bit (16 bits per channel, RGB)
• Alpha channel: Yes — full 8-bit or 16-bit transparency
• Animation: No — animated PNGs require the APNG extension, which is not part of the core PNG spec (though most modern browsers support it)
• Metadata: Supports text chunks (author, copyright, description) and ICC color profiles
• Interlacing: Optional — allows a low-resolution preview to appear while the image loads

The lossless compression is the defining characteristic. When you save a JPEG, the encoder discards some image data to reduce file size — that data is gone permanently. PNG never discards data. You can save, re-open, edit, and re-save a PNG indefinitely without quality loss.

PNG vs Other Formats

The right format depends on the image content and intended use. Here is how PNG compares to the formats you will encounter most often:

Key points:

• PNG vs JPEG: PNG is lossless, JPEG is lossy. A PNG photograph will be 3-5x larger than the equivalent JPEG with minimal visible quality difference. Use PNG for graphics, JPEG for photos. See the full breakdown in our JPEG vs JPG guide and compare both against modern alternatives in Best Image Format for the Web.
• PNG vs WebP: WebP lossless compression produces files roughly 26% smaller than equivalent PNGs, according to Google's benchmarks. WebP also supports animation and lossy compression. If browser compatibility is not a constraint (and in 2026, it is not — all major browsers support WebP), WebP lossless is the better choice for most PNG use cases. Read the full comparison at PNG vs WebP.
• PNG vs GIF: GIF is limited to 256 colors per frame. PNG supports millions of colors with full alpha transparency. The only reason to choose GIF over PNG is animated GIF compatibility in specific tools or platforms.

For a deeper look at the bitmap format that PNG replaced alongside GIF, see What is BMP? and What is TIFF? for another lossless alternative.

When to Use PNG (and When Not To)

Use PNG for:

Logos and brand graphics. Logos contain sharp edges, flat colors, and often need transparency. PNG preserves every edge exactly. A JPEG logo will show compression artifacts — visible distortion around high-contrast edges — especially at smaller sizes.

Screenshots. Screenshots contain text, UI elements, and sharp transitions. Lossless compression keeps everything readable. JPEG compression makes text look fuzzy.

Text-heavy images. Any image that contains text — diagrams, slide exports, infographics with labels — should be PNG. Lossy compression degrades text faster than any other element.

Images requiring transparency. Only PNG, WebP, and GIF support transparency. PNG's alpha channel is the most capable: it supports partial transparency (translucent shadows, smooth edges), while GIF only supports fully transparent or fully opaque pixels.

Images that will be edited and re-saved. If an image is a working file that will go through multiple save cycles, PNG's lossless nature prevents quality degradation. JPEG loses quality every time it is saved.

Do not use PNG for:

Photographs. A photograph contains millions of similar colors with no sharp edges. Lossless compression has little to work with — PNG files of photographs are enormous. The same photo as a JPEG at quality 85 will look nearly identical and be 4-6x smaller. For photographs delivered on the web, use JPEG or WebP lossy.

Hero images and full-width backgrounds. These are typically photographs or complex gradients. See above — use JPEG or WebP.

Video thumbnails. JPEG or WebP.

When file size is the constraint. If you need the smallest possible file and can accept some quality loss, JPEG or WebP lossy will beat PNG significantly on photographs and complex imagery.

How to Convert To and From PNG

Converting between image formats is straightforward with the right tool. Pixotter's convert tool handles all common conversions client-side — your images never leave your browser.

To convert to or from PNG on Pixotter:

1. Go to pixotter.com/convert
2. Drop your image file (JPG, WebP, AVIF, GIF, BMP, TIFF, or other PNG)
3. Select PNG as your output format (or select another format if converting from PNG)
4. Download the converted file

The conversion happens in your browser via WebAssembly — no upload, no server round-trip, no waiting. Large batch conversions work the same way.

When converting from JPEG to PNG, the output file will be lossless but larger. The original JPEG artifacts are now frozen in lossless form — converting to PNG does not recover lost quality from previous JPEG compression.

When converting from PNG to JPEG or WebP, you are introducing lossy compression for the first time. Choose quality settings carefully — 85-90% JPEG quality is usually the right balance of size and fidelity.

How to Compress PNG Without Losing Quality

PNG is already compressed, but you can often reduce file size significantly without touching image quality. This is true lossless compression: the output is bit-for-bit identical to the input when decoded.

How it works: PNG uses the DEFLATE algorithm to compress image data. Different encoders make different trade-offs between compression speed and compression ratio. The default encoder in Photoshop, macOS, and most tools optimizes for speed. A dedicated PNG optimizer (like the one powering Pixotter's PNG compressor) spends more time finding better compression patterns, resulting in smaller files with no quality loss.

Typical reductions from lossless PNG compression:

• Screenshots: 20-40% smaller
• Logos with flat colors: 30-60% smaller
• Photographs saved as PNG: 5-15% smaller (less room to work with)

To compress your PNG files on Pixotter:

1. Go to pixotter.com/compress
2. Drop one or multiple PNG files
3. Pixotter applies lossless optimization automatically
4. Download the compressed files

The compressed files are visually identical to the originals. You can verify this by comparing them in any image viewer — there is no visible difference because no data was changed, only the encoding efficiency improved.

If you need even smaller files than lossless compression provides, consider switching to WebP lossless or accepting lossy compression. For a step-by-step guide, see How to Compress PNG.

FAQ

What does PNG stand for?

Portable Network Graphics. The format was created in 1996 as a free, patent-unencumbered replacement for GIF.

Is PNG lossless?

Yes. PNG uses lossless compression — every pixel in the original image is preserved exactly. You can save and re-open a PNG file indefinitely without quality degradation.

Can PNG files have transparent backgrounds?

Yes. PNG supports a full alpha channel, which means pixels can be fully transparent, fully opaque, or anywhere in between. This makes PNG the standard format for logos, icons, and any graphic that needs to sit on a variable background.

What is the difference between PNG and JPG?

The fundamental difference is compression. PNG is lossless — it preserves every pixel. JPEG is lossy — it discards some image data to reduce file size. For photographs, JPEG is more efficient. For graphics with sharp edges, text, or transparency, PNG is the right choice.

Why is my PNG file so large?

PNG files of photographs are large because lossless compression has little to work with in complex, high-detail imagery. If your PNG is a photograph, convert it to JPEG or WebP for significant size savings. If it is a graphic or logo, run it through a PNG optimizer — you can often reduce size by 30-50% without any quality loss.

Can PNG files be animated?

The core PNG specification does not include animation. The APNG (Animated Portable Network Graphics) extension adds animation support, and most modern browsers support APNG. However, APNG files are not always labeled distinctly from PNG — they use the .png extension and will display as a static image in tools that do not support APNG.

What is the difference between PNG-8 and PNG-24?

PNG-8 uses an indexed color palette with up to 256 colors, similar to GIF. PNG-24 uses full RGB color (16.7 million colors) with optional 8-bit alpha. PNG-8 produces smaller files for simple graphics; PNG-24 is the standard for complex graphics requiring full color depth or smooth transparency. Most modern PNG files are PNG-24.

Should I use PNG or WebP for my website?

For new projects targeting modern browsers (which covers virtually all traffic in 2026), WebP lossless is the better choice for graphics that previously would have been PNG. WebP lossless files are roughly 26% smaller at equivalent quality. Use PNG when you need maximum compatibility with older tools, email clients, or specific platforms that do not support WebP. For a full comparison, see PNG vs WebP.