Glossary · Speed and HTTP
Response time is how long a service takes to answer a request, measured from sending the request to receiving the full response, usually in milliseconds.
For a website check it includes the DNS lookup, connecting, the TLS handshake, the server’s processing (the wait for the first byte) and downloading the response. Splitting it into these phases shows where the time goes: a slow server phase points at the application or database, slow DNS or TLS at infrastructure.
Report response time with percentiles. The median is the typical experience; the 95th percentile shows the slow tail that an average hides.
Response time from a monitoring check isn’t page load time in a browser, which adds images, scripts and rendering. It is the part the server controls, and a rise is often the first sign of trouble before an outage.
Response time = DNS + connect + TLS + server wait + download
Example: 38 ms DNS + 21 ms connect + 44 ms TLS + 182 ms server + 15 ms download = 300 ms.
Every Uptimecheck HTTP check records the response time split into DNS, connect, TLS, server and download, with charts of the median and the 95th percentile. Set “Alert when slower than” to get a slow alert after three checks in a row above the limit, and another when it is fast again; slow time doesn’t count as downtime.
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Response time is how long your server takes to answer a request, not how long the page takes to load. What counts as good, why monitors and browsers measure differently, and what slows sites down.
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Ten practical ways to make your website load faster, from a CDN and image optimization to caching, compression and server response time.
ReadFor a web page’s HTML from a nearby location, under about 200 ms is fast and over a second is slow. APIs depend on the work they do; set a limit from your own baseline, such as twice the usual 95th percentile.
Each check opens a new connection, so DNS, connect and TLS are paid every time, while your browser reuses connections and caches. The distance between the check location and the server adds latency too.
No. Latency is the delay of the network path; response time adds the server’s processing and the download.
Set up your first monitor in under a minute, or look around the live demo first.
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