AVIF vs PNG: File Size, Transparency, and Which Format to Choose
PNG is the dominant lossless image format on the web, valued for its perfect image reproduction and full transparency support. AVIF delivers the same transparency features with far smaller file sizes. Here is when to use each.
Why PNG Files Are So Large
PNG uses DEFLATE compression, a lossless algorithm. Every pixel is stored exactly as it appears. For photographs, this is wildly inefficient. A 1200x800 photograph can reach 2 to 4 MB as a PNG. The format was designed for screenshots, UI graphics, and images with flat color regions where lossless preservation matters.
Web developers frequently use PNG for product images on transparent backgrounds, logos, and UI icons. The transparency support (full 8-bit alpha channel) is irreplaceable for these use cases, but the file sizes balloon when applied to photographs.
How AVIF Handles Transparency
AVIF supports full alpha channel transparency, identical in capability to PNG. Transparent areas in the source image compress efficiently using AVIF's advanced prediction tools, unlike PNG where transparent regions still occupy storage space proportional to their pixel count.
An e-commerce product image on a transparent background saved as PNG might be 400 KB. The same image converted to AVIF typically comes in under 80 KB with no visible difference at normal viewing resolution.
Important: When converting PNG images with transparency to AVIF, use a tool that preserves the alpha channel. Our free converter on this site handles transparent PNGs correctly.
File Size Comparison: AVIF vs PNG
| Image Type | PNG Size | AVIF Size | Reduction |
|---|---|---|---|
| Product on white bg | 380 KB | 65 KB | -83% |
| Logo with transparency | 45 KB | 8 KB | -82% |
| Screenshot (1440px wide) | 1.2 MB | 180 KB | -85% |
| Photograph (1200x800) | 2.8 MB | 55 KB | -98% |
| UI illustration | 90 KB | 22 KB | -76% |
For photographic content, AVIF's lossy compression compared to PNG's lossless mode creates dramatic size differences. For graphics with flat colors, gains are smaller but still substantial.
Lossy vs Lossless: The Core Trade-off
PNG is always lossless. Every pixel is stored exactly. AVIF in its default (lossy) mode introduces minimal artifacts to achieve its compression advantages. For most web delivery use cases, this difference is invisible to the human eye at quality settings above 60.
AVIF also supports a lossless mode. Lossless AVIF typically produces files 10 to 20 percent larger than lossless WebP for graphical content, but 20 to 30 percent smaller than PNG. For photographic lossless content, AVIF lossless does not outperform PNG significantly. The real win is in lossy AVIF vs PNG lossless for photographs.
When PNG Is Still the Right Choice
Keep PNG for
- Source files and design assets that will be edited again
- Pixel-perfect screenshots where exact color accuracy is required
- Archival storage of original artwork
- Favicons and small icons where pixel precision matters
- Images destined for print production workflows
Switch to AVIF for
- Web delivery of any image, including those with transparency
- Product images in e-commerce
- Blog post images and editorial photography
- Hero banners and promotional graphics
- Any image where file size affects page load time
Serving AVIF with a PNG Fallback
For images with transparency that need broad compatibility, use the <picture> element:
<picture> <source srcset="product.avif" type="image/avif"> <img src="product.png" alt="Product image" width="600" height="600"> </picture>
Modern browsers load the AVIF. Browsers without AVIF support load the PNG. Both maintain transparency correctly.
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