WebP is the best default image format for most website images in 2026. It produces files 25–35% smaller than JPEG at the same perceptual quality, supports transparency, and has universal browser support. Use PNG for screenshots and diagrams requiring lossless quality, SVG for logos and icons, and AVIF if your stack supports it and you need the maximum compression gains.
| Format | Best for | Compression | Transparency |
|---|---|---|---|
| WebP | Photos, most web images | 25–35% better than JPEG | Yes |
| JPEG | Photos, legacy systems | Baseline | No |
| PNG | Screenshots, diagrams, UI | Lossless | Yes |
| SVG | Logos, icons, illustrations | Vector — scales perfectly | Yes |
| AVIF | Image-heavy pages, modern stacks | ~50% better than JPEG | Yes |
Why WebP won the format debate for most websites
WebP has been supported by all major browsers since 2020 (Chrome, Firefox, Safari, Edge). The compatibility concern that made JPEG the "safe" choice for most of the 2010s no longer applies. For a website targeting any modern audience, WebP is safe to use as the primary format.
The compression advantage is real and consistent: at the same SSIM quality score, WebP files are typically 25–35% smaller than JPEG equivalents. For a product image that would be 150KB as JPEG, WebP brings it to roughly 100–110KB. Multiplied across a page with 10 images, that's 400–500KB less to download — a meaningful difference for mobile users on slower connections.
WebP also supports transparency (alpha channel), which JPEG doesn't. A product image with a transparent background that previously required PNG — often 3–5× larger than JPEG — can now be served as lossy WebP with transparency at roughly JPEG file sizes. That's the combination that makes WebP genuinely better, not just marginally different.
When PNG is still the right choice
PNG uses lossless compression — it preserves every pixel exactly. That's what you need for:
- Screenshots of UIs, code editors, or applications where text must be perfectly sharp
- Technical diagrams with fine lines and precise detail
- Images with large areas of identical color where JPEG compression creates visible banding
- Source files you'll edit further — saving from a lossless source prevents quality degradation
WebP lossless exists and is supported, but PNG lossless remains more universally supported in editing tools and workflows. For images that genuinely need lossless quality, PNG is still the practical choice unless you have a pipeline that handles WebP lossless natively.
SVG: the format most people underuse
SVG is a vector format — it describes shapes mathematically rather than storing pixel grids. An SVG logo at 20KB scales perfectly to any size from 16px favicon to billboard without quality loss. The equivalent PNG at retina resolution might be 200–500KB.
SVG is the right format for: company logos, navigation icons, simple illustrations, charts generated from data, and anything that needs to look sharp at multiple sizes. Most design tools (Figma, Illustrator, Sketch) export SVG directly.
SVG is wrong for: photographs, complex illustrations with thousands of shapes, or anything where the file size of the SVG description exceeds what a raster format would produce — which happens with very complex vector artwork.
AVIF: better than WebP, but not yet the default
AVIF (AV1 Image File Format) achieves around 50% better compression than JPEG at equivalent quality — better than WebP's 25–35%. Browser support is solid (Chrome since 2020, Firefox since 2021, Safari since 2023), but encoder support in popular tools is still catching up.
The practical barrier is encoding speed. AVIF encoding is significantly slower than WebP or JPEG — a batch conversion that takes seconds in WebP might take minutes in AVIF. For sites with large image libraries or automated pipelines, this overhead is the main adoption friction.
If you're building a new site with a modern image CDN (Cloudflare Images, Imgix, Cloudinary), these services can serve AVIF automatically where the browser supports it and fall back to WebP or JPEG otherwise. In that scenario, AVIF is worth enabling. For a site where you're manually preparing images, WebP is more practical today.
The Core Web Vitals connection
Image format directly affects Largest Contentful Paint (LCP) — the time until the largest visible element loads. LCP is one of Google's Core Web Vitals and a documented ranking factor. Google's PageSpeed Insights flags JPEG and PNG images as an "opportunity" when they could be replaced with WebP or AVIF.
Switching your hero image and above-the-fold photos to WebP is one of the highest-impact format changes. Compress web images to under 200KB and serve in WebP format — that combination covers the two biggest image-related LCP improvements available without infrastructure changes.
See our full guide on JPEG vs PNG vs WebP for a deeper comparison of compression behavior and when each format shows its limits.