Image Optimization for Google: The Complete Checklist
Image-heavy pages routinely see 20–40% traffic lifts from proper image SEO. This is the full checklist we use — every item is directly tied to a documented Google ranking signal or Core Web Vital.
1. Serve next-gen formats
Convert PNG and JPEG to WebP or AVIF. Expected savings: 30–70% file size, direct LCP improvement.
2. Right-size every image
Never serve a 3000px image displayed at 800px. Use srcset for responsive images, or a CDN that resizes on the fly.
3. Compress aggressively
Quality 75–85 is visually indistinguishable from 100 for almost all photos. AltPixel defaults to quality 0.9 for a safety margin.
4. Write real alt text
See our alt-text guide. Every image needs unique, descriptive, keyword-natural alt text under 125 characters.
5. Descriptive filenames
`golden-retriever-puppy.jpg` beats `IMG_1234.jpg`. Google reads filenames as a ranking signal for image search.
6. Lazy-load below-the-fold images
Add `loading="lazy"` to every <img> that isn't visible on initial paint. Native browser support is universal.
7. Set explicit width and height
Prevents cumulative layout shift (CLS) — one of Google's three Core Web Vitals.
8. Submit an image sitemap
Add <image:image> tags to your sitemap.xml. Speeds up Google Images indexation dramatically.
9. Use structured data on product images
Product schema with an `image` field is required for Google Shopping surfaces and rich results.
10. Serve from a fast CDN
Cloudflare, Bunny, or Fastly. Image latency directly hits LCP.
Frequently asked questions
What's the single highest-impact image SEO change?
For most sites: converting hero images to WebP or AVIF. It's the fastest way to improve LCP, which is a direct Google ranking factor.
Do I still need image alt text if I have descriptive captions?
Yes. Alt text serves screen readers and image search; captions serve sighted readers. They complement, not replace.
How many images should be on a page for SEO?
As many as add value — but each should be optimized. A cluttered page with 40 unoptimized images ranks worse than the same page with 40 WebP images and unique alt text.
Skip the manual work
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