Time to First Byte (TTFB)
What is Time to First Byte?
Time to First Byte (TTFB) is the time between a browser requesting a page and receiving the first byte of the server’s response. It includes any redirects, the DNS lookup, connecting and negotiating TLS, and the time the server takes to produce the response. Google’s web.dev guidance treats 0.8 seconds or less as good.
TTFB is not a Core Web Vital, but it comes before all of them. Nothing can render until the HTML starts arriving, so a slow TTFB pushes back Largest Contentful Paint and First Contentful Paint by the same amount.
High TTFB usually comes from slow database queries or rendering on the server, no page caching, a server far from the visitor, or chains of redirects before the final URL.
Why Time to First Byte matters for SEO
A slow server makes every page slow, and it is often the cause when LCP fails even though the page itself is light. It also affects crawling: Google’s crawler slows down when a site responds slowly, which can matter for large sites with tight crawl budget.
How to reduce TTFB
- Measure from real locations. Field TTFB appears in PageSpeed Insights, and the browser’s Network panel shows it for a single request.
- Cache full pages where you can, on the server or at a CDN edge, so most requests skip the backend.
- Profile slow pages on the server and fix the slow queries, API calls or templates.
- Serve visitors from nearby locations with a CDN.
- Remove redirects in front of the final URL, such as http to https to www hops; see redirect chains.
- Use modern protocols (HTTP/2 or HTTP/3) and keep TLS configuration current.
Time to First Byte FAQ
What is a good TTFB?
Google’s web.dev guidance treats 0.8 seconds or less as good and over 1.8 seconds as poor, measured from real visits. Faster is better, since it limits how quickly anything else can load.
Is TTFB a Core Web Vital?
No. It is a supporting metric. It matters because it delays LCP, which is a Core Web Vital.
Related SEO terms
Page speed is how quickly a page loads, shows its content and responds to input. Google measures it mainly through Core Web Vitals.
Core Web Vitals are Google’s three metrics for real-world page experience: Largest Contentful Paint, Interaction to Next Paint and Cumulative Layout Shift.
Largest Contentful Paint (LCP)
Largest Contentful Paint (LCP) is a Core Web Vital that measures when the largest image or text block in the viewport appears. Good is 2.5 seconds or less.
CDN (content delivery network)
A CDN (content delivery network) is a network of servers around the world that caches and serves your site from locations close to each visitor.
A redirect chain is when a URL redirects to another URL that redirects again, so it takes two or more hops to reach the final page.
Crawl budget is the set of URLs Google can and wants to crawl on a site. It only becomes a constraint on very large or fast-changing sites.