Why image size matters
Photos are usually the heaviest files on a firm's website. A portrait or office photo straight from a camera or phone is often 3 to 8 MB and 4000 pixels or more wide, while the page shows it in a box a few hundred pixels across. Every visitor still downloads the full file, which slows the page on mobile networks, delays Largest Contentful Paint and makes Google's Core Web Vitals worse.
Resizing an image to the largest size it is actually displayed at and saving it as WebP or a well-compressed JPEG commonly cuts its weight by 80 to 95%, with no visible difference at normal viewing size. It is one of the few speed fixes that needs no developer.
How the optimizer works
The tool uses your browser's built-in image decoder and encoder (File API, canvas and, where available, a background Web Worker). Your images are never uploaded: this page has no upload endpoint, and the processing happens on your own device, so it also works for confidential photos.
Images are scaled down, never up, and keep their aspect ratio, unless you choose the social-share size, which crops from the centre to 1200 × 630. Camera rotation (EXIF orientation) is applied so portraits stay upright. Re-encoding removes metadata such as camera details and GPS location, and converts colours to sRGB, the colour space of the web.
- Formats: keep the original format, or convert to WebP, JPEG or PNG. AVIF output is not offered because browsers cannot encode it natively.
- Transparency is kept in PNG and WebP. JPEG has no transparency, so transparent areas are filled with white and the tool warns you.
- If an optimised file would be larger than your original, the tool says so and offers the original instead.
- Limits keep your browser responsive: up to 25 images and 250 MB per batch, 40 MB and 50 megapixels per image.
Which size to choose
A quality setting around 75 to 82 for WebP and JPEG is a good default for photos. Use PNG only for screenshots, logos and graphics with flat colours or text; for photos it produces much larger files.
- Hero or banner image: 1920 pixels wide covers full-width headers on most laptop and desktop screens.
- Images inside pages and articles: 1200 pixels wide is sharp in a typical content column, including on high-density phone screens.
- Team and portrait photos: 800 × 800 pixels at most is plenty for profile cards and team grids.
- Social share image (og:image): exactly 1200 × 630 pixels, the size LinkedIn, Facebook and most messaging apps expect for link previews.
After you download
Upload the new files in place of the old ones in your CMS. In WordPress, upload the resized image and let it generate its smaller versions for srcset. Keep descriptive, lowercase file names with hyphens — the tool suggests them — and write alt text describing each meaningful image.
Then run our image optimization audit on the page to confirm what is left: images displayed smaller than their file size, missing width and height attributes, or a lazy-loaded hero image.