Latency, and the part of it you can change
Latency is delay: the time between a packet leaving your device and a reply coming back. This latency test measures it over UDP to the nearest Cloudflare edge, 50 times a second for 15 seconds by default. After the run you see four figures in the detail panel: the lowest latency any packet achieved, the average, the 95th percentile and the highest.
The lowest figure is the closest thing to your connection's fixed latency. It is set by the type of line you have and the distance to the edge, and you can only change it by changing provider or technology. Everything above that minimum is waiting: packets sitting in a wifi retry, a router queue or a congested link. That extra is the part you can usually reduce, and the gap between the minimum and the 95th percentile tells you how big it is.
Typical latency by connection type
If your minimum sits well above the range for your connection type, the extra is in the fixed part of the path: a weak wifi link, a long run of copper, or a provider that routes traffic a long way before it reaches the internet. If your minimum is normal but the median or 95th percentile is high, the problem is queueing, and that is usually fixable at home.
| Connection | Typical latency |
|---|---|
| Fibre to the home | 2 to 15 ms |
| Cable | 10 to 30 ms |
| DSL / VDSL | 15 to 45 ms |
| 4G / 5G mobile | 25 to 70 ms |
| Low-orbit satellite (Starlink) | 25 to 60 ms |
| Geostationary satellite | 550 to 700 ms |
Latency and speed are different things
A 1 Gbps connection can have worse latency than a 50 Mbps one. Speed is how much data the line can carry per second; latency is how long any one piece of it takes to make the trip. Downloads care about speed. Games, calls, remote desktops and even the snappiness of loading a web page care about latency, because each of them waits for a reply before doing the next thing.
That is also why this test does not download anything large. A latency test that runs during a speed test measures the delay the speed test itself causes. If you want to know how your latency behaves when the line is full, read what bufferbloat is and run this test while something else downloads.
Lowering latency
- Use a cable for anything latency-sensitive. It removes the wifi part of the queue entirely.
- Stop background uploads. Upload queues grow much faster than download queues on most home lines.
- Turn on smart queue management (SQM) or a similar feature on your router if it has one. It keeps queues short when the line is busy.
- Pick game and call servers near you. No setting at home can beat the speed of light to a distant server.