Latency test
Measures how long a round trip from your browser to our test node in Chicago takes, first on an idle line and then while the line is busy. Loaded latency is the number that decides how responsive your connection feels.
"Test under load" adds short download and upload bursts to show bufferbloat.
Latency trace
Teal is idle, amber is under load, red marks a packet with no reply.
Distribution
How often each round-trip time occurred.
The distribution appears after the first test.
Diagnostics from Chicago (US)
These tests run from our test node in Chicago (US), not from your browser. Use them to check whether a host is reachable and how far it is from a US Midwest network. Private and internal addresses can't be tested.
Latency, ping and RTT
Latency is the delay between sending data and getting a response. "Ping" and "round-trip time (RTT)" are the same measurement: the time for a packet to reach a server and come back. This test reports the median RTT, plus the fastest and slowest samples.
The browser tests send small timestamped messages over a WebSocket to our test node in Chicago (US) and time each reply. Because a WebSocket runs over TCP, a lost packet is retransmitted rather than vanishing, so it shows up as a late reply; anything that takes longer than two seconds is counted as lost. For raw ICMP loss from a server, use the network echo test further down the page.
Idle latency versus loaded latency
Most speed tests report latency on an idle line, which is the best case. Real use is rarely idle: a video call shares the line with downloads, updates and other people. When a router queues too much data, latency can rise from 20 ms to several hundred.
Press "Test under load" to measure both. A small rise is normal; a rise of more than about 100 ms means bufferbloat, which you can grade on the bufferbloat test page.
What affects latency
- Distance to the server: about 1 ms of round trip per 100 km of fiber.
- The access technology: fiber and cable are usually lower than DSL, satellite or mobile.
- Wi-Fi signal and interference in your home.
- Congestion on your line or at your provider at busy times.
- Queueing in your router when the line is saturated (bufferbloat).
Questions
How do I test my latency?
Press "Start latency test" for idle latency, or "Test under load" to also measure latency while the line is busy. Both take under 20 seconds.
Is 27 ms latency good?
Yes. 27 ms is good for every common use, including competitive gaming and video calls.
What is a good latency score?
Under 20 ms is excellent, 20 to 50 ms is good, 50 to 100 ms is acceptable, and over 150 ms is poor for calls and games. Loaded latency should stay within about 30 ms of idle latency.
Is latency the same as ping?
In everyday use, yes. Ping is a tool that measures round-trip latency, so people use the words interchangeably.