Viewport meta tag
Also known as responsive viewport · mobile viewport meta
A <meta name="viewport"> tag tells mobile browsers to match the layout width to the device screen, enabling responsive, mobile-friendly rendering.
What it is
The viewport meta tag is placed in <head> and controls how a page is scaled and sized on mobile devices. The standard value width=device-width, initial-scale=1 maps CSS pixels to the device's actual width so a responsive layout displays correctly.
Why it matters
Without it, mobile browsers assume a desktop-width canvas and shrink the page, hurting usability and mobile rankings under Google's mobile-first indexing. Since Google predominantly crawls and evaluates the mobile version, a correct viewport is foundational for both traditional and AI search visibility.
How to verify
View source and confirm <meta name="viewport" content="width=device-width, initial-scale=1"> in <head>. Test in DevTools device toolbar or Chrome's Lighthouse, which flags pages that lack a properly configured viewport.
How to fix
Add <meta name="viewport" content="width=device-width, initial-scale=1"> to the <head> of every page. Avoid disabling zoom with maximum-scale=1 or user-scalable=no, as that harms accessibility, and pair the tag with genuinely responsive CSS.
Related terms
- Page performanceHow quickly and smoothly a page loads and becomes interactive, commonly measured by server response time, HTML weight, and Core Web Vitals.
- Image alt textThe alt attribute on an <img> provides a text description of the image for screen readers, search engines, and cases where the image fails to load.
- Title tagThe <title> element in a page's <head> defines its canonical name, shown as the clickable headline in search results and as the browser tab label.
- HTTPS with HSTSServing every page over HTTPS encrypts traffic, and the HSTS response header forces browsers to use HTTPS for all future requests to the domain.
Official references
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