What exactly is image SEO?
Image SEO is optimizing your images so search engines can understand them and so they don't slow your site down. It has two goals: earning traffic from Google Images, and protecting your page speed (a ranking factor) by keeping image files light.
For creators and online business owners, image SEO is underrated free traffic. Google Images is one of the largest search engines in the world, and product photos, recipe images, and how-to visuals all attract clicks when optimized properly.
How should I name image files for SEO?
Name image files descriptively with hyphens between words, before you upload them. Google reads filenames to understand image content, so blue-ceramic-coffee-mug.jpg communicates far more than DSC_0294.jpg.
- Use real words that describe the image.
- Separate words with hyphens, not underscores or spaces.
- Keep it concise — three to five words is ideal.
- Include a keyword naturally, but don't stuff.
| Image SEO step | Bad | Good |
|---|---|---|
| Filename | IMG_4821.jpg | walnut-cutting-board.jpg |
| Alt text | (empty) | "Handmade walnut cutting board" |
| Format (photo) | PNG, 4MB | JPEG 80%, 280KB |
| Dimensions | 4000px wide | Sized to display (1200px) |
| Hero image weight | 2MB+ | Under 400KB |
How do I write alt text that helps SEO?
Write alt text that describes the image clearly in a sentence, as if explaining it to someone who can't see it. Alt text serves accessibility first and SEO second — both are satisfied by a natural, accurate description.
For an online store, "handmade walnut cutting board with juice groove" is excellent alt text: it's descriptive, useful to screen-reader users, and naturally contains the terms a shopper would search. Avoid keyword stuffing like "cutting board cheap cutting board buy cutting board" — Google penalizes it and screen readers find it useless.
What's the right file size and format for web images?
For photographs, export JPEG at around 80% quality and resize to the dimensions your page actually displays. This is the core of image performance SEO. An image shown at 800px wide should not be uploaded at 4000px wide.
Aim to keep most content images under 200KB and hero images under 400KB. Use the converter to compress and resize in one step, and consider exporting a WebP copy for an additional 25–35% saving on supported browsers.
How does image optimization affect Core Web Vitals?
Large images are the most common cause of a poor Largest Contentful Paint (LCP) score, one of Google's three Core Web Vitals. The LCP element on most pages is the hero image, so a heavy hero directly drags down the score Google uses for ranking.
Compressing and correctly sizing your images is the single most effective way to improve LCP. Combine that with specifying width and height attributes (to prevent layout shift) and you address two of the three Core Web Vitals through image work alone.