PNG vs WebP vs AVIF: In-Depth Comparison — What's the Optimal Image Format for 2026?

In web performance optimization, choosing the right image format is crucial. As of 2026, with PNG, Google's WebP, and the next-generation AVIF format becoming more widespread, which format should you choose? This article provides a thorough comparison of these three formats from the perspectives of file size, image quality, browser support, and tool support.

Characteristics of each format

PNG（Portable Network Graphics）

PNG is a lossless image format introduced in 1996. It supports transparency (alpha channel) and is widely used for screenshots, logos, and icons. While its compression ratio is lower compared to other formats, it has the advantage of zero image quality degradation.

• Compression method: Lossless compression
• Transparency support: Yes (alpha channel)
• Animation: supported with APNG
• Browser support: Supported on all browsers

WebP

WebP is an image format developed by Google in 2010. It supports both lossless and lossy compression, achieving approximately 26% file size reduction compared to PNG with lossless compression and 25–34% reduction compared to JPEG with lossy compression. As of 2026, all major browsers support it, and there are virtually no practical compatibility issues.

• Compression method: Both lossless and lossy
• Transparency support: Yes
• Animation: yes
• Browser support: All of Chrome, Firefox, Safari, and Edge are supported

AVIF（AV1 Image File Format）

AVIF is an image format based on AV1 video codec technology, and its adoption began around 2020. It achieves even higher compression rates than WebP, reducing file size to approximately 50% of WebP and 70% or more of PNG at equivalent quality. However, the drawback is its slower encoding speed.

• Compression method: Both lossless and lossy
• Transparency support: Yes
• Animation: yes
• Browser support: Chrome 85+, Firefox 93+, Safari 16.4+, Edge 121+

File Size Comparison

The following shows approximate file sizes when saving the same image in each format (lossy compression, quality 80).

As this comparison shows, AVIF is the most efficient for photos and screenshots. However, note that PNG values are lossless compression and should not be considered a strict quality comparison.

Which format should you choose

The current recommendation as of 2026 is to choose based on your use case.

• <strong>Logos, icons, transparent images</strong> — PNG or SVG. Use PNG exclusively if lossless quality is required
• <strong>Photos, thumbnails</strong> — Use AVIF as the primary choice and WebP as fallback
• <strong>CMS & blog articles</strong> — WebP is a safe choice, displaying correctly in nearly all environments
• <strong>Performance first</strong> — Fallback in order AVIF → WebP → PNG using <code>&lt;picture&gt;</code> element

<picture>
    <source srcset="image.avif" type="image/avif">
    <source srcset="image.webp" type="image/webp">
    <img src="image.png" alt="説明文" loading="lazy">
</picture>

Conversion tools and methods

Here we introduce how to convert from the command line.

# PNG → WebP（cwebp を使用）
cwebp -q 80 input.png -o output.webp

# PNG → AVIF（avifenc を使用）
avifenc --min 20 --max 30 input.png output.avif

# ImageMagick での一括変換
magick mogrify -format webp -quality 80 *.png

Test image file

For operation verification and upload testing of each format, please use DevLab's test image files.

• <a href="/ja/files/images/png/">PNG Test Files</a> — Various sizes from 10KB to 100MB
• <a href="/ja/files/images/webp/">WebP Test Files</a> — For WebP support verification
• <a href="/ja/files/images/">Image Test Files</a> — View all formats in a list

Summary

As of 2026, WebP is already a stable choice, and AVIF is gaining support from major browsers. For new projects, we recommend implementing progressive fallback using the <code>&lt;picture&gt;</code> element and actively adopting AVIF. However, PNG continues to play an important role in scenarios requiring lossless compression and image editing workflows.