Optimise Images for SEO
Core Web Vitals, LCP budgets and PageSpeed Insights — every SEO-critical image preset a technical SEO or WordPress admin needs.
SEO image optimisation in 2026 is Core Web Vitals engineering. Google's Largest Contentful Paint threshold is 2.5 seconds on mobile — on a real 4G connection with typical latency, that translates to roughly 100–200 KB delivered for the LCP element. Anything larger risks a failing CWV score, which is a documented ranking signal. That's the underlying constraint every preset on this hub is tuned to.
Beyond LCP, PageSpeed Insights flags images that could be encoded more efficiently — usually meaning uncompressed PNGs on photographic content, or JPEG where WebP would be smaller. The efficient encoding audit reliably passes at WebP quality 78 for photographic content, or PNG quality 90 for graphics. And for og:image and Twitter card scrapers, JPEG at quality 85 at 1200 × 630 is the format that maximises social preview compatibility across every scraper you don't control.
For the underlying image-delivery mechanics — Next.js Image component, CDN pipelines (Cloudflare Images, BunnyCDN, imgix), lazy loading — see the dedicated presets below. For deeper technical work on hero images, blog inline images, and product page mains at site scale, cross-reference the /optimise-images-for-websites hub.
Core Web Vitals (LCP, PageSpeed)
Presets tuned to pass Core Web Vitals LCP and PageSpeed Insights' efficient-encoding audit.
Content & template roles
Presets by content role: blog inline, thumbnails, product pages, backgrounds and editorial. Each has a different CWV budget and quality target.
Social previews & CDN pipeline
og:image, Twitter card, Next.js Image component sources, and CDN storage — the delivery-side of SEO image work.
Related tools
Frequently asked questions
- What's the LCP image size ceiling in 2026?
- Under 100 KB WebP for the reliably-passing CWV LCP element on mobile. Up to 200 KB is workable on well-cached, well-served sites with short connection RTT. Above 200 KB, LCP failure becomes likely on real-world 4G.
- WebP or AVIF for SEO?
- WebP for now. AVIF produces smaller files (10–20% better) but encoding is 10–50× slower, which pushes the cost onto the CDN or build pipeline. If your CDN can handle AVIF encoding at scale (Cloudflare Images, BunnyCDN), use AVIF. For build-time pipelines, WebP is the pragmatic choice.
- Does PageSpeed Insights punish oversized images even below the fold?
- Yes. The 'Efficiently encode images' audit flags any image that could be encoded more efficiently, regardless of fold position. But the LCP audit is the one with the direct ranking impact — that's the element to focus on first.
- Should I lazy-load below-the-fold images?
- Yes — with the native loading="lazy" attribute, or via Next.js's <Image> component which lazy-loads by default. But never lazy-load the LCP element itself; that's the mistake most sites accidentally make.
- Is my image uploaded anywhere when I use the presets?
- No. Every preset compresses in your browser. Files never touch our servers.