Image SEO: How to Name, Compress & Optimize Photos for Google
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 keeping your pages fast by keeping image files light. Google says Core Web Vitals are used by its ranking systems, though it still shows the most relevant content first.
For creators and online business owners, image search can bring visitors, and product photos, recipe images and how-to visuals can all attract clicks.
How should I name image files for SEO?
Name image files descriptively with hyphens between words, before you upload them. Google says a filename gives it “very light clues” about an image and recommends short, descriptive names, so blue-ceramic-coffee-mug.jpg says more than DSC_0294.jpg.
- Use real words that describe the image.
- Separate words with hyphens, not underscores or spaces.
- Keep it short but descriptive.
- 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+ | As light as it can be while looking right |
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 says it gives a poor experience and may cause your site to be seen as spam, and it tells screen-reader users nothing.
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.
Use the compress tool to compress and resize in one step, and consider WebP: Google reports WebP lossy images are 25–34% smaller than comparable JPEGs at equal SSIM quality.
How does image optimization affect Core Web Vitals?
Largest Contentful Paint (LCP) is one of Google’s three Core Web Vitals, with Interaction to Next Paint (INP) and Cumulative Layout Shift (CLS). Google calls LCP good at 2.5 seconds or less, INP at 200 milliseconds or less and CLS at 0.1 or less, measured at the 75th percentile of page loads. On 73% of mobile pages the LCP element is an image (HTTP Archive, 2024).
A lighter image helps, but on most slow sites it is not the main delay: Google’s analysis found that most sites with poor LCP spend less than 10% of that time downloading the image, and far more waiting for the download to start. So make the main image light, and also let the browser find it early — for example, don’t lazy-load it. Add width and height attributes to images so the page doesn’t jump while they load; that is the CLS side.
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