PNG is one of the most widely used image formats on the web, known for its lossless compression and support for transparency. But it was designed in 1996, and file sizes show it. WebP, Google's modern image format, can produce files 25–50% smaller than PNG at equivalent quality — with full transparency support and no visible degradation for most web content.
If you're serving PNG images on a website and care about page load speed, converting to WebP is one of the most impactful optimisations you can make.
Why PNG Files Are Large
PNG uses lossless compression, which means it preserves every pixel exactly as encoded. This makes it ideal for screenshots, diagrams, logos, and any content where sharp edges and text legibility matter. The tradeoff is that lossless compression has a ceiling — there's only so much redundancy it can remove from a complex image.
A photograph saved as PNG will typically be 3–5× larger than the same image as a JPEG, and still 25–40% larger than a well-encoded WebP.
How WebP Compares to PNG
WebP offers both lossless and lossy compression modes:
Lossless WebP — produces a pixel-perfect output like PNG, but typically 25–35% smaller. This is the right choice when you need to preserve every detail: logos, icons, screenshots with text, UI assets.
Lossy WebP — introduces minimal, controlled compression artifacts to achieve 50–80% smaller files than PNG. For photos, illustrations, and images with gradients where exact pixel accuracy isn't critical, lossy WebP looks visually identical to PNG at a fraction of the size.
Both modes support transparency (alpha channel), so WebP is a drop-in replacement for PNG in every use case that requires it.
Browser Support in 2026
WebP is supported in all major browsers:
- Chrome — since 2011
- Firefox — since version 65 (2019)
- Safari — since version 14 (2020)
- Edge — since version 18 (2019)
Global support is above 97%. For practical purposes, you can serve WebP to all modern browsers without a fallback, unless you specifically need to support very old iOS devices (iOS 13 and earlier).
When to Convert PNG to WebP
Definitely convert: - Photos or photographic illustrations saved as PNG (they're unnecessarily large) - Any PNG image served on a web page where load performance matters - Background images, hero images, product photos in PNG format - PNG images larger than 100 KB on a public-facing website
Consider keeping as PNG: - Assets used inside design tools (Figma, Sketch, Photoshop) that need round-trip lossless editing - Images distributed to users who might open them in older software - Favicons and small UI icons (where WebP's advantages are minimal at tiny sizes)
How to Convert PNG to WebP
Convly's PNG to WebP converter converts PNG files to WebP entirely in your browser using WebAssembly. No upload, no server, no size limit. Drop your PNG file, download the WebP result in seconds.
Steps:
- Open the PNG to WebP tool
- Drag your PNG file onto the converter, or click to browse
- Click Convert
- Download the WebP file
Transparency is preserved automatically — if your PNG has an alpha channel, the output WebP will too.
Typical File Size Savings
| Image type | PNG size | WebP size | Savings | |------------|----------|-----------|---------| | Photography | 2.4 MB | 480 KB | ~80% | | UI screenshot | 800 KB | 520 KB | ~35% | | Logo with transparency | 120 KB | 80 KB | ~33% | | Simple icon | 15 KB | 10 KB | ~33% |
These figures vary by content, but consistent 30–50% savings are typical for real-world web assets.
WebP in HTML: Using
If you need to support older browsers alongside modern ones, the
<picture>
<source srcset="image.webp" type="image/webp">
<img src="image.png" alt="Description">
</picture>Modern browsers pick image.webp; anything that doesn't understand WebP falls back to image.png. In 2026, for most projects this level of fallback is optional — but it's a clean pattern if you need it.
PNG to WebP vs AVIF
If you want to go further than WebP, AVIF offers an additional 20–30% size reduction over WebP for photographic content. However, AVIF encoding is significantly slower and software support outside browsers is still limited.
For a practical comparison of these next-generation formats, see What is AVIF? →.
Summary
Converting PNG to WebP is a straightforward, high-impact optimisation. Lossless WebP preserves every pixel while producing files 25–35% smaller than PNG. Lossy WebP can cut sizes by 50–80% for photographic content. Both modes support transparency. With 97%+ browser support, WebP is the right default image format for web delivery in 2026.