PNG vs WebP vs AVIF: How to Choose Image Formats and Conversion Methods
Image format selection is one of the most critical factors affecting website loading speed. As of 2026, the main options are <strong>PNG / JPEG / WebP / AVIF</strong>. This article organizes the characteristics, use cases, and browser support for each format, and explains how to choose the optimal format.
Format comparison table
| Format | Compression method | Transparency | Animation | Image quality | File Size | Browser support |
|---|---|---|---|---|---|---|
| PNG | Lossless | ✅ | APNG | Maximum (no degradation) | Large | All browsers |
| JPEG | Lossy (Lossy) | ❌ | ❌ | Quality adjustment available | Small to Medium | All browsers |
| WebP | Lossless / Lossy | ✅ | ✅ | Better than JPEG | JPEG 25-35% Smaller | 95%+ |
| AVIF | Lossy / Lossless | ✅ | ✅ | Better than WebP | 20% smaller than WebP | 92%+ |
Which format should you choose
When to Choose PNG
- <strong>Logos, icons, screenshots</strong> and other cases where quality degradation is unacceptable
- Images containing text (becomes hard to read if blurred by compression)
- When transparency is required and IE11 support is needed (rarely necessary)
When to Choose JPEG
- When <strong>maximum compatibility</strong> is needed for photos and images with many gradients
- For email attachments or delivery to legacy devices
When to choose WebP (recommended)
- <strong>Most website images</strong> — 25–35% smaller compared to JPEG
- Transparency + compression together (PNG alternative)
- Animation (GIF alternative — much smaller)
- Browser support rate is 95%+, so there are virtually no issues
When to Choose AVIF (Cutting-edge)
- <strong>When pursuing minimum file size</strong> — 20% smaller than WebP
- When you want to keep high-quality photos as lightweight as possible
- Browser support: 92%+ (Safari 16+, Chrome 85+, Firefox 93+)
Implementation Pattern: Switching with the <code>picture</code> Element
The most robust approach is to specify multiple formats using the <code><picture></code> element. The browser selects the first source it supports.
<picture>
<source srcset="image.avif" type="image/avif">
<source srcset="image.webp" type="image/webp">
<img src="image.jpg" alt="Description" loading="lazy">
</picture>With this method, AVIF-compatible browsers will load AVIF, WebP-only compatible browsers will load WebP, and incompatible browsers will load JPEG.
Convert with a tool
<a href="/ja/tools/image-convert/">DevLab's image format conversion tool</a> lets you convert between PNG ⇄ WebP ⇄ JPEG ⇄ AVIF using only your browser. Use the quality slider to balance file size and image quality while converting. No server upload needed, so your privacy is protected.
Related: Use the <a href="/ja/tools/exif/">EXIF viewer</a> to check photo metadata and remove location information, or <a href="/ja/tools/image-base64/">image to Base64 conversion</a> to generate inline Data URLs.
Summary
- When in doubt, choose <strong>WebP</strong> — best balance
- For even smaller sizes, use <strong>AVIF</strong> (with fallback via picture)
- If lossless required, use <strong>PNG</strong>
- Use <strong>JPEG</strong> if maximum compatibility is required