Website response time test
Break a request into its four stages — DNS, TCP connect, TLS handshake and time to first byte — so you can see exactly where the milliseconds go.
The four stages
1. DNS lookup
Turning the hostname into an address. Should be under 50 ms from a warm cache. Persistently slow DNS points to an under-provisioned or distant nameserver — a good reason to use an anycast DNS provider.
2. TCP connect
The three-way handshake. This is essentially your network distance to the server: one round trip, no more. If connect time is high but ping is low, something in the path is rate-limiting new connections.
3. TLS handshake
Negotiating encryption, typically one or two extra round trips. TLS 1.3 cut this to one. A handshake that costs much more than the connect time suggests an old TLS version, a needlessly long certificate chain, or an OCSP lookup blocking the response.
4. Time to first byte
Everything above, plus the time your server spent actually building the page. Subtract the first three stages and what remains is application time — the database queries, the template rendering, the API calls. That is the number you can usually improve most, with caching.
What good looks like
- Under 200 ms total TTFB — excellent; typical of a cached or static page on a CDN.
- 200–500 ms — good for a dynamic site doing real work.
- 500–1000 ms — noticeable; users perceive the delay before anything appears.
- Over 1 s — a problem worth engineering time. Start with the slowest database query and page caching.
FAQ
Is this the same as a PageSpeed score?
No. This measures the server's response, not how quickly the browser renders the finished page. A fast server with a heavy front end still feels slow — but a slow server can never feel fast.
Why does the first check look slower than the second?
Cold caches: DNS, TLS session data and often the site's own page cache. Run a check two or three times and use the later numbers.
How do I improve time to first byte?
Cache full pages where you can, put a CDN in front, fix the slowest queries, and keep the server close to your visitors. In that order, usually.
Related reading
Other tools
Website status checker
Is it up, how fast, and what is it running?
Ping test
Round-trip latency and packet loss.
DNS lookup
A, AAAA, MX, NS, TXT, SOA and CAA records.
SSL certificate checker
Expiry, issuer, chain and hostname match.
HTTP header & security check
Every response header, graded for security.
Open port checker
Which TCP ports answer from the outside.
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