# Image SEO Image SEO is making images findable and making them help the page. You do it once per image and you see the gain on load time and on queries with image intent. This page gives you the checklist, how to measure, and the traps to avoid. Updated 2026-09-14 · Source: https://porteur.ai/glossary/image-seo ## What Image SEO covers on one image Image SEO lets an image be found and lets it help the page. On one image, set: - A descriptive file name, like pricing-chart.png, not IMG_1234.png. - An alt attribute that describes the image, accessibility first: alt="Line chart of Pro vs Team usage". - Width and height attributes so the layout does not shift. - A modern format: AVIF or WebP, with a JPEG or PNG fallback only if needed. - A size that fits the viewport and device. Serve the smallest that looks clean. - Lazy loading below the fold, and do not lazy load images above the fold. Give the first image priority. - Structured data that includes the image property on the thing the page is about. - For large libraries, an image sitemap or images listed in your XML sitemaps. - A caption or clear surrounding text that says what the image shows. On a page like /guides/getting-started, that means the hero image loads fast, has width and height, and the alt says what is shown, not why it exists. ## The speed side that helps every page Images often decide your Core Web Vitals. The largest image is often the LCP element. Aim for LCP under 2.5 seconds, CLS under 0.1, INP under 200 ms. - Compress AVIF or WebP until artifacts show, then back off one step. - Export multiple widths and use srcset and sizes so the browser picks the smallest fit. - Inline or preload only the single above the fold hero if it is your LCP image. Do not overuse it. - Set width and height on every img to prevent layout shift. - Do not ship text as an image. Use real text for headings and buttons. A fixed /pricing will load its plan grid screenshots as 800w WebP on mobile and 1600w on desktop, with CLS steady at 0.0 because sizes are set. ## How to measure Image SEO - In Search Console, Performance, switch Search type to Image to see queries and clicks from Google Images. - Still in Performance, on Web type, sort queries that include words like "diagram", "logo", "screenshot", to spot image-driven intent. - Open a page in PageSpeed Insights. Check LCP element type. If it is an image, fix format, size, and priority first. - Track Core Web Vitals over 28 days. Watch the LCP trend after you change hero images. - Crawl a sample page in your browser DevTools, Network tab. Confirm the chosen srcset candidate size and format match the device. Expect Google Images to send traffic to some pages and almost none to others. The speed gains matter to all pages either way. ## What Google Images sends and how to earn it Google Images can send discovery traffic on visual queries. Product photos, diagrams and step by step shots do well. Stock-looking art rarely does. - Use unique visuals. A labelled diagram on /product/architecture beats a generic illustration. - Put the image near the relevant heading and paragraph. The text tells Google what it shows. - Use structured data with the image property on Product, Article or SoftwareApplication as fits the page. - Use a clean, readable image URL. Place product photos under /images/products/ where you can. ## Common traps to avoid > Do not stuff keywords in alt text. Describe the image so a screen reader user understands it. Leave decorative images with empty alt. - Shipping only PNGs or JPEGs when AVIF or WebP would cut size a lot. - Lazy loading the hero image, which delays LCP. - Missing width and height, which causes layout shift and hurts CLS. - Serving a 3000px wide image into a 360px viewport. - Relying on captions alone. The paragraph above or below should also say what is shown. ## Questions ### What is SEO for images? SEO for images is the work that makes images findable and makes them help the page. It covers file names, alt text, size, format, loading strategy, structured data, and context on the page. ### How do I create an SEO friendly image? Export a clean AVIF or WebP at the smallest width that looks good. Name it descriptively, set width and height, write a plain alt that describes it, place it next to relevant text, and avoid lazy loading if it is above the fold. ### What are the best practices for image SEO? Describe the image in alt text, accessibility first. Use AVIF or WebP, set width and height, serve responsive sizes with srcset, lazy load below the fold, include the image in structured data, and add a caption when it helps the reader. ### How do I know if Google Images brings me traffic? Open Search Console, Performance, change Search type to Image. Check queries, pages, impressions and clicks. Compare to Web type to see where images support page clicks rather than drive them. ### How long should alt text be? Keep it concise and factual. One short sentence is enough in most cases. Describe what it shows, not the file name or keywords you want to rank for. ### Which image format should I use for SEO? Use AVIF when it renders well in your stack, else WebP. Fall back to JPEG or PNG only when the modern format is not supported or quality demands it, such as crisp UI shots. ## Read next - [Image optimisation for page speed: the hero image and everything below it](https://porteur.ai/guides/image-optimisation-for-page-speed): Fix the hero image first for LCP, then lazy-load the rest. Choose AVIF or WebP, set srcset and sizes, and add width and height to stop shift. - [Lazy loading images: what to lazy-load and what never to](https://porteur.ai/guides/lazy-loading-images): Lazy loading images saves bandwidth. Here is what to lazy-load, what never to, how to handle iframes and backgrounds, and how it affects LCP and SEO. - [Core Web Vitals for a product site: the three numbers](https://porteur.ai/guides/core-web-vitals): The product founder’s guide to LCP, CLS and INP: what Google measures, why phones decide the pass, common causes, and how to test and fix. - [Largest Contentful Paint (LCP)](https://porteur.ai/glossary/largest-contentful-paint): Largest Contentful Paint is when the biggest element appears. Aim under 2.5 s. See how to measure it, usual causes on small sites, and quick fixes. - [Cumulative Layout Shift (CLS)](https://porteur.ai/glossary/cumulative-layout-shift): Cumulative Layout Shift is how much a page moves while loading. Keep CLS at or below 0.1. Here is how to measure, find causes, and fix them. - [The Search Console performance report, column by column](https://porteur.ai/guides/search-console-performance-report): Every column in the Google Search Console performance report explained with the traps that trip small sites, and how to act on each. - [AI-generated images on a product site](https://porteur.ai/guides/ai-images-and-seo): Where a generated image is fine, where only a real screenshot will do, what Google reads about an image, and what provenance metadata records. Drop your homepage URL to get a free check that scans your images, the searches around them and your rivals on them, then shows three findings in about thirty seconds. Free check: https://porteur.ai/