JPG to WebP
Convert JPG images to WebP in your browser to cut file size ~30%. Free, private, no upload; ideal for faster web pages.
About this tool
Serving WebP instead of JPG typically cuts image weight by 25-35% at the same visual quality, which directly improves page speed and Core Web Vitals. This tool converts JPG to WebP locally in your browser: drop in images, download smaller ones.
It is aimed at anyone hand-optimizing images for a website: bloggers, shop owners, and developers who want smaller assets without setting up a build pipeline or trusting an upload service with client work.
Common uses
- Shrink blog or product images before uploading to WordPress or Shopify
- Optimize site assets for Lighthouse and Core Web Vitals scores
- Batch-convert a folder of JPGs for a static site
Automate via API
The same conversion is available as a REST endpoint for scripts, pipelines, and backends. POST the file, get the converted file back:
curl -X POST https://formatably.com/api/v1/tools/jpg-to-webp \ -H "X-Api-Key: YOUR_API_KEY" \ --data-binary @photo.jpg \ -o photo.webp
Direct requests accept up to 4 MB; the large-file flow handles up to 100 MB. Both are covered in the API documentation · Get an API key
Cutting page weight for Core Web Vitals
If Lighthouse or PageSpeed Insights flagged "Serve images in next-gen formats" on your site, this is the fix: convert your JPGs to WebP and re-upload them. Start with the images that matter most for the score, which is usually the large hero or product photo that counts as your Largest Contentful Paint element, then work through the rest.
Keep your original JPGs as masters and treat the WebP files as the versions you serve. Re-encoding a WebP again later stacks compression loss, so when you need a new size or crop, go back to the original.
Where you upload the WebP depends on your platform. WordPress has accepted WebP in the media library since version 5.8, so converted files upload like any other image. Shopify converts product photos to WebP automatically on its CDN, so this tool is mainly useful there for theme assets and images you host elsewhere. On a hand-built site, just swap the file and update the extension in your HTML.
JPG notes
JPG (JPEG) is the universal photo format: every camera, phone, website, printer, and government upload form accepts it. It compresses photos well but does not support transparency, and each re-save loses a little quality.
- JPG has no transparency; transparent areas are filled with white during conversion.
- JPG is lossy: converting into it trades a small amount of quality for compatibility and size.
WebP notes
WebP is Google's web image format, around 25-35% smaller than JPEG at the same quality, with support for transparency and animation. It is everywhere on the web, and notoriously unwelcome everywhere else: editors, printers, and upload forms.
- Images saved from websites are frequently WebP even when the URL said .jpg.
- Animated WebP needs a format that supports animation on the other side (GIF); converting to PNG or JPG keeps the first frame.
- WebP supports transparency; converting to JPG fills transparent areas with white.
Frequently asked questions
How much smaller will my images get?
Typically 25-35% smaller than the source JPG at equivalent visual quality (this tool encodes at 90% quality). Results vary with content; photos with fine detail compress less than flat graphics.
Do all browsers support WebP now?
Yes. Every browser released since 2020, including Safari 14+, displays WebP. The compatibility concerns that existed years ago are gone for websites, though desktop software support still lags.
Are my files uploaded to a server?
No. The conversion runs entirely in your browser using WebAssembly and the canvas API; your files never leave your device. There are no ads and no trackers on tool pages. You can verify this yourself: open your browser's developer tools, watch the Network tab while converting, and you will see no upload requests. It even works offline once the page has loaded.
Is there a file size limit?
In the browser there is no hard limit; you are bounded only by your device's memory, and files of a few hundred megabytes are usually fine. The REST API accepts files up to 4 MB in a direct request, or up to 100 MB using the large-file upload flow described in the API docs.
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