What is TTFB?
If page load time refers to the complete load of a web page in the browser window, what is the mysterious acronym TTFB? Time To First Byte is the parameter used to measure the reactivity of a web server or another network resource. It is calculated by counting the time between a HTTP (or HTTPS) client request and the receipt of the first web page byte. In other words, it indicates the web server speed by starting a data transmission with a client, usually a browser or a search engine spider and it is measured in milliseconds. The TTFB is composed by three parts:
- connection time
- time needed to send the HTTP request
- time needed to get the first byte of the web page
The measurement of TTFB always includes the network latency, that is the reason why using a server able to get very low latencies is so important and helps to reduce TTFB. Unlike page load time, which refers to the complete load of the web page on the browser and so to its display on the device screen, TTFB is a parameter that is not perceived by users, but it is relevant for any website anyway.
How measure and evaluate TTFB
To measure TTFB you can use several tools available online, as Webpagetest, or Google Chrome and Google Analytics instruments. Once you get the TTFB value, you can evaluate the web server reactivity using the following guidelines:
0,1 – 0,2 seconds: very good
0,3 – 0,5 seconds: good
0,6 – 0,9 seconds: average
1 – 1,5 seconds: above the average
1,6 seconds or slower: very bad
To achieve a better result is possible to optimize the Time To First Byte with different specific actions: we will describe them in the next post, stay tuned!
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