About JPG to WebP
If images are going onto a web page, converting them from JPG to WebP is close to free performance. WebP was designed as a direct replacement for JPG and it is meaningfully better at the job: typically 25–35% smaller for the same visual quality, sometimes more on images with large areas of flat colour.
Browser support is not a concern any more. Every current version of Chrome, Firefox, Safari and Edge decodes WebP. The old advice about serving a JPG fallback alongside it has been obsolete for years. If your audience is people using web browsers, you can ship WebP alone.
On quality. The default here is 85 rather than 90, because WebP holds detail better than JPG at the same number — a WebP at 85 generally looks like a JPG at 90 while being smaller still. This is a re-encode of already-lossy data, so the sensible approach is to convert from the highest-quality JPG you have rather than from something already squeezed. If your source is a heavily compressed JPG, its artefacts are baked in and WebP will faithfully preserve them.
Where JPG still wins. Anything leaving the web. Email attachments, files sent to a printer, images going into older design software or a client's unpredictable machine — JPG remains the safest thing to hand over. Convert for the web; keep JPG for people.
A useful sequence. Resize first, then convert. A 4000-pixel photograph shown in an 800-pixel column carries twenty-five times more pixels than it can display, and no format choice recovers that. Resizing to the display size and then converting to WebP compounds both savings and usually produces a file a fraction of the original.
Conversion runs entirely in your browser — nothing is uploaded, and batches of up to 30 files are processed one at a time so memory stays under control.
Questions
How much smaller will the files be?
Typically 25–35% at matched visual quality, and more on images with large flat areas.
Do all browsers support WebP?
Yes — every current version of Chrome, Firefox, Safari and Edge. JPG fallbacks have not been necessary for years.
Why is the default quality 85 and not 90?
WebP retains detail better than JPG at the same number, so 85 in WebP looks roughly like 90 in JPG while being smaller.
Should I convert images I am emailing?
No. Keep JPG for anything going to a person or a printer. WebP is for the web, where the browser is the destination.