How to Optimize Images for SEO

Image optimization supports accessibility and loading performance. Ranking gains cannot be promised.

How to use this tool

1
Choose a format for the image content and required compatibility.
2
Resize to useful display sizes and compare compressed outputs.
3
Write contextual alt text and descriptive filenames.
4
Reserve layout space and use appropriate loading priorities.
5
Measure real pages after publishing and adjust based on the results.

Recommended Tools

Common Mistakes

  • Using one quality setting for every image.
  • Deleting originals before inspecting outputs.
  • Assuming a smaller file proves better visual quality or search rankings.

Pixel dimensions

Choose output dimensions from the intended display or print size. Keep aspect ratio to avoid stretching. With both width and height set, the image fits inside that box; it is not cropped to fill it. Enlarging pixels does not create missing detail.

Quality and transparency

Start with a moderate quality value and compare the downloaded file with the original. Results depend on the image and browser encoder. The on-page thumbnail shows the source image, not a before/after comparison. PNG quality is not controlled by the quality slider.

Descriptive image content

Use descriptive filenames, useful captions and alt text that explains the image in context. Avoid keyword stuffing. Smaller image files can help loading when images are a bottleneck, but no conversion or compression setting guarantees search-ranking improvements.

Image delivery

Set width and height or CSS aspect-ratio so the page can reserve space. Use responsive image sizes where appropriate. Load the main image promptly and consider lazy-loading images below the fold. Measure the published page on mobile; a format change alone does not guarantee better LCP, CLS or INP.

Frequently Asked Questions