CORE WEB VITALS & PERFORMANCE
Time to First Byte: what it means and how it works
How long the server takes to start answering; a diagnostic that feeds LCP.
- Intermediate level
- 2 primary sources
- Reviewed 29 October 2026
- TopicCore Web Vitals & performanceAlso in Technical SEO
- LevelIntermediateAssumes the basics of how search works
- Also calledTTFB
- Sources2 primary sourcesweb.dev, Google Search Central
- Reviewed29 October 2026Re-checked every 12 months
On this page
Quick definition
Time to First Byte (TTFB) is the time from when a browser starts navigating to a page until the first byte of the response arrives. It includes redirects, DNS lookup, connection setup and the server’s processing time. It is a diagnostic metric, not a Core Web Vital, and web.dev suggests 0.8 seconds or less as a rough guide.
Why it matters
Nothing renders until HTML arrives, so TTFB sets the floor for every loading metric, including LCP. Slow responses also reduce how much Googlebot crawls: Google lowers its crawl rate when a server responds slowly.
What makes it slow
- Redirect chains before the final URL.
- No page caching, so every request runs database queries (common on WooCommerce and large WordPress sites).
- Distant servers without a CDN for visitors in another region.
- Slow plugins, external API calls made during page generation, or an overloaded host.
How to check it
- Look at field TTFB in PageSpeed Insights or CrUX for real visitors.
- Compare cached and uncached responses; logged-in and cart pages are usually uncached.
- Check the response time chart in Search Console‘s Crawl stats for Googlebot’s view.
Common mistakes and misconceptions
Myth TTFB is a Core Web Vital.
In fact It is a supporting diagnostic metric. It affects LCP, which is a Core Web Vital.
Check it on your site
Free tools, no sign-up
- FreeCore Web Vitals CheckerCheck a page’s real-user LCP, INP and CLS from the Chrome UX Report, for the page and its whole site.Open the tool
- FreeHTTP Header AnalyzerSee every response header a URL sends and check the ones that matter for indexing, security and caching.Open the tool
- FreeRedirect Chain CheckerFollow every redirect from a URL, hop by hop, with status codes and timings, and spot chains, temporary redirects and dead ends.Open the tool
In the NdovuSEOLabs platform
Run the same checks on every page of your site, with your own data.
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Sources and review
- Time to First Byte (TTFB) web.dev
- Crawl budget management for large sites Google Search Central
Written and maintained by Ndovu SEO Labs. First published 29 October 2026. Facts last checked against the sources above on 29 October 2026. How we write and review the glossary.