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WebP vs PNG: format differences and use cases
Choosing between WebP and PNG depends on transparency requirements, file size targets, browser support, and whether lossless output is required. Both formats can produce lossless files, but they get there with different compression techniques, and that difference is most of why WebP files usually come out smaller.
What this guide explains
Choosing between WebP and PNG depends on transparency requirements, file size targets, browser support, and whether lossless output is required. Both formats can produce lossless files, but they get there with different compression techniques, and that difference is most of why WebP files usually come out smaller.
Technical scope
This guide describes browser-based file workflows, format tradeoffs, and ConvertUnlimited processing boundaries for supported tools.
Technical difference
PNG is a lossless format that has been the standard for transparent images for decades. WebP is a newer format developed by Google that offers both lossy and lossless compression, often resulting in much smaller files than PNG. PNG compresses pixel data with DEFLATE, the same general-purpose algorithm ZIP uses, applied after a per-scanline filtering step, and it has no lossy mode at all. Lossless WebP (VP8L) instead uses techniques built for images specifically, including a color-indexing transform for graphics with few distinct colors and a color cache, which is why Google's own published comparison found lossless WebP files roughly 26% smaller on average than PNG files of the same source image, even though neither format discards pixel data.
Comparison Table
| Feature | WebP | PNG |
|---|---|---|
| Compression | Lossy & Lossless | Lossless |
| Transparency | Supported | Supported |
| File Size | Smaller (roughly 26% less in Google's lossless comparison) | Larger |
| Compression method | Spatial prediction, color-indexing transform, and color cache (VP8L) | DEFLATE (zlib) with per-scanline filtering |
| Metadata support | Optional EXIF/XMP chunks via VP8X | Limited EXIF support via an optional chunk some newer encoders write |
| Best for | Web delivery, photos, mixed transparency use | Logos, icons, screenshots, lossless graphics |
Pros and Cons
WEBP
- Often smaller file size
- Supports both lossy and lossless modes
- Strong browser support
- Not ideal for high-end print
- Older software might lack support
- Lossless mode is not always smaller than a well-optimized indexed PNG
PNG
- Lossless quality (no data loss)
- Universal software support
- Preserves sharp edges
- Needs no format-support fallback
- Often large file sizes
- Only supports lossless compression
When PNG can still win
Lossless WebP is usually smaller, but not always. For very simple graphics with only a handful of flat colors — basic icons, simple logos, screenshots of mostly solid UI — an 8-bit indexed PNG (a palette of up to 256 colors) can sometimes match or beat lossless WebP, because the image already compresses well with a simple palette and DEFLATE. The size advantage of lossless WebP is most consistent on photographic detail, fine gradients, and complex illustrations, where general-purpose compression has less to work with.
Browser support and fallback
PNG has universal, decades-long support and needs no fallback plan. WebP is supported by every current major browser, but any browser or operating-system version older than when each vendor added support cannot display it. Sites that still need to support those older versions typically serve WebP inside a picture element with a PNG fallback image, rather than replacing PNG outright.
When to Use Each
Use WebP for modern web delivery when smaller files are useful and the publishing workflow supports the format. Use PNG when transparency, sharp edges, screenshots, or lossless graphics are more important than file size, or when the file needs to work in older software with no WebP support at all.
Editing software support
PNG opens and saves in essentially any image editor released in the last two decades. WebP support in editing software has spread over time rather than arriving everywhere at once: current versions of most mainstream editors can open and export it, but older installed versions, some niche or industry-specific tools, and some workflow automation scripts built years ago may only recognize PNG and JPEG. Check your specific editing pipeline rather than assuming WebP support if you rely on tools you have not recently updated.
Related guides
FAQ
Does WebP support transparency like PNG?
Yes, WebP supports alpha channel transparency just like PNG, but usually at a much smaller file size.
Is WebP better than PNG for SEO?
WebP can help performance when it produces smaller files, but SEO depends on many page-level factors. Use WebP when it improves delivery without breaking compatibility.
Can I convert PNG to WebP in the browser?
Yes. Use the ConvertUnlimited image converter to decode selected PNG files and write WebP output locally in the browser for supported workflows.
Is lossless WebP always smaller than PNG?
Usually, but not in every case. Simple graphics with very few colors can sometimes compress just as well, or better, as an 8-bit indexed PNG. The size advantage is most reliable on photographic or detailed images.
Does converting PNG to WebP change the pixels?
Only if you use lossy WebP. Lossless WebP output reproduces the source pixels exactly, the same guarantee PNG makes; lossy WebP trades some pixel accuracy for a smaller file.
Can every image editor open a WebP file the way it opens a PNG?
Not necessarily. Current versions of most mainstream editors support WebP, but older installed versions and some specialized tools may only recognize PNG and JPEG. Confirm support in your specific software before standardizing a workflow on WebP.
Action
Convert between PNG and WebP in the browser: PNG to WebP or WebP to PNG.