TTFB Checker
Measure Time to First Byte (TTFB) for any URL — see how fast your server responds and identify bottlenecks.
Did this tool work for you?
How to use this calculator
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Enter the full URL you want to test.
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Click "Check Now" to send a request and measure the server response time.
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TTFB is the time from the request being sent to receiving the first byte of the response.
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Under 200ms is excellent; over 600ms needs optimization.
Frequently asked questions
What does the TTFB figure actually measure?
It is the time, in milliseconds, from our server starting the request until the response headers arrive. That span includes DNS lookup, the TCP and TLS handshakes, any redirects that are followed, and the time the site takes to start answering. It is measured with one GET request from our server, so it is a single sample and reflects that server’s distance from the site, not your visitors’.
Why do repeated runs give different numbers?
A single request is affected by cold caches, connection set-up, load on the site and network conditions, and cached results from the last minute or so may be reused. Run the check several times and look at the typical value, ignoring the first run if the site is rarely visited. One slow reading is not a diagnosis.
How are the ratings decided?
The Rating line uses four bands: Excellent under 200 ms, Good under 400, Needs improvement under 600 and Slow beyond that. The colour follows: green under 400, amber from 400 to 599, red from 600. Web.dev suggests 800 ms or less as a good TTFB, so the tool’s bands are stricter than that guidance.
Does a redirect affect the result?
Yes. Redirects are followed automatically, and their time is included in TTFB. Entering example.com/ without www, if the site redirects to the www version, adds a full extra round trip. Use the redirect checker to see each hop, or enter the final URL to measure the page alone.
What is Total Load?
It is the time from the start of the request until the whole response body has been read as text. It is not a browser load time: images, scripts and rendering are not included. Page Size is the character count of the decoded text divided by 1024, shown in kilobytes, and covers the HTML only.
What do the Server and Transfer-Encoding lines show?
Server shows the server response header if the site sends one and a dash otherwise. Transfer-Encoding shows that header (for example chunked) or none. Many sites hide the server header, or show the name of a CDN instead of the origin software.
Why did my request fail or time out?
The tool waits up to 15 seconds for the response. A longer wait, a refused connection, an invalid certificate, or a DNS failure ends the check with an error rather than a timing. Sites that block automated requests may also return a 403 or a challenge page quickly, which would produce a fast but meaningless TTFB. Check the Status Code line.
Why can I not measure TTFB for localhost?
The measurement is taken from our server, which can only reach public internet hosts, and local or private addresses are blocked. Even for a public site the figure includes the distance between our server and yours, so it will differ from what visitors in other regions see.
Time to First Byte: what the measurement includes and how to act on it
Definition and what the tool does
Time to First Byte is the delay between sending a request and receiving the beginning of the reply. It combines network set-up with server think time: resolving the name, opening the connection, negotiating TLS and waiting while the server builds or fetches the page. This checker makes one GET request, follows redirects, and stops its timer when the response headers arrive. It then reads the rest of the body to report Total Load and Page Size, together with the status code and the Server, Content-Type and Transfer-Encoding headers.
Bands used by the tool
The rating labels and colours use different cut-offs, shown here.
| TTFB | Rating line | Colour |
|---|---|---|
| Under 200 ms | Excellent | Green |
| 200 to 399 ms | Good | Green |
| 400 to 599 ms | Needs improvement | Amber |
| 600 ms and over | Slow | Red |
Using the result
Test your home page and one deeper page, such as a category or a search results page, because dynamic pages are usually slower than cached ones. A high figure on every page points at the platform: slow hosting, no page caching, a distant origin server with no CDN, or a slow TLS handshake. A high figure on only some pages points at the application, such as heavy database queries. If a CDN is in front of the site, repeat the test: the second request is often served from cache and much faster, which shows the cache works. Always note the status code, since a redirect or error response has its own timing.
Example inputs and common causes of slow responses
Enter the full address, for example https://example.com/, and then the same page with a different scheme or host form (http:// or www) to see how much a redirect adds. If TTFB is close to the Total Load, the HTML is small and the delay is waiting, not downloading. Typical remedies include enabling full-page caching, adding a CDN, upgrading the hosting plan, reducing slow database calls, keeping connections alive, and removing unneeded redirects. Because the measurement comes from one location, a site that is quick for your own visitors can still look slower here, and the reverse is also possible. For region-by-region data, a field-data source such as the Chrome User Experience Report is more representative.
Learn more from an authoritative source:
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →