Most image optimisation advice starts with compression settings and quality sliders. Those matter, but they come second. The more important decision happens before you open any tool: which format are you using? For websites, that decision increasingly means WebP — and the reason is specific enough to be worth understanding rather than just following as a rule.
The problem with JPG and PNG on the modern web
JPG was standardised in 1992. PNG followed in 1996. Both were designed for the hardware, connection speeds, and display technology of that era. They work fine — everything supports them — but neither was designed with modern web performance in mind. JPG's compression algorithm was state of the art thirty years ago. PNG's lossless compression produces larger files than necessary for photographic content. Both formats leave file size on the table that WebP recovers.
This matters more than it used to because Google incorporated page speed into ranking signals through Core Web Vitals — measurable performance metrics that affect search ranking. The metric most directly affected by image format is Largest Contentful Paint (LCP): how quickly the largest visible element on the page loads. For most pages, that element is an image. A hero image in WebP loads faster than the same image in JPG, which improves LCP, which can improve ranking. The connection between image format and SEO is real, but it runs through this specific mechanism rather than any direct format preference from Google.
What WebP does differently
WebP uses a more sophisticated compression model than JPG. Where JPG divides an image into 8×8 pixel blocks and compresses each independently, WebP uses variable block sizes and predictive coding — it analyses surrounding pixels to predict values rather than encoding everything from scratch. The result is roughly 25–35% smaller files than JPG at equivalent visual quality for photographs.
WebP also supports lossless compression (like PNG) and transparency (like PNG), making it a single format that handles use cases previously requiring two separate formats. A site that switches to WebP throughout can replace both JPG and PNG with one format, simplifying the decision for every image.
Browser support
WebP is supported in Chrome, Firefox, Safari, and Edge — all current major browsers. Safari added full support in version 14 in 2020. The main exception is Internet Explorer, which has no WebP support and is no longer maintained by Microsoft. For most sites today, IE traffic is negligible enough that a fallback isn't necessary. If it is, the HTML <picture> element handles it:
<picture>
<source srcset="image.webp" type="image/webp">
<img src="image.jpg" alt="Description of the image">
</picture>Converting and integrating WebP
Portimg's converter handles JPG and PNG to WebP in the browser without any software installation. Upload one or multiple files, select WebP, download. No account required, files deleted after processing.
The order of operations matters for maximum savings: resize images to their actual display dimensions first, then convert to WebP. A 4000px image converted to WebP and then scaled down in the browser still forces the browser to download a large file. Resizing first, then converting, compounds the savings from both steps.
For recurring workflows, automation is more practical than manual conversion. WordPress plugins like ShortPixel and EWWW Image Optimizer convert images to WebP automatically on upload. Frameworks like Next.js and Nuxt have built-in image components that handle WebP conversion and serving. CDNs including Cloudflare and Bunny.net convert and serve WebP based on browser support without changing your upload workflow.
Where WebP is and isn't right
WebP is the right default for any image going onto a website: blog images, product photos, hero images, thumbnails, background images. The file size reduction is consistent, quality is maintained, and browser support is effectively universal for current web traffic.
It's not the right choice for print files, professional editing originals, or images shared in non-web contexts with unknown software support. For print, use TIFF. For archival originals, use a lossless format your editing software supports natively. For images distributed as standalone files to recipients whose software you don't know, JPG remains the most reliably compatible option.
The practical rule: if the image is going on a website, convert to WebP. If it's going anywhere else, check what the destination requires first.