Takes about 20 seconds
Settings
Server: the nearest Cloudflare data centre, chosen automatically. Load: speed.cloudflare.com.
What this page measures: both. It times small web requests (HTTP round trips) to the nearest Cloudflare data centre, one every 0.2 seconds: first on a quiet line for about 5 seconds, then for 8 seconds while your browser downloads from speed.cloudflare.com and 8 seconds while it uploads there. You get idle latency (median) and how much it rises under download and under upload. Full method.
What latency is
Latency is delay: the time data needs to get from one point to another. Most tests measure round-trip time, from your device to a server and back, as described in IETF RFC 2681. It is counted in milliseconds. Bandwidth is how much data fits through the pipe; latency is how long each piece takes to get through.
Idle vs. loaded latency
Latency on a quiet line tells you the best your connection can do. Latency while the line is busy, sometimes called "working latency", tells you how it behaves in real life when someone is streaming or uploading. The gap between the two is the core of bufferbloat; our bufferbloat test measures it directly.
What adds latency
- Distance: signals take time to cross cables and oceans.
- Connection type: different access technologies add different amounts of delay.
- Queues: data waiting in router and modem buffers.
- Wi‑Fi: radio retries and interference.
How to reduce latency
You can't shorten the distance to a server, but you can remove avoidable delay: use a cable, choose nearby servers in games and apps, and keep queues short with Smart Queue Management, explained in How to fix bufferbloat.
What’s good? Our colour guide
| Extra latency under load | Range |
|---|---|
| Good | up to 30 ms extra |
| OK | more than 30, up to 200 ms extra |
| High | more than 200 ms extra |
These are the labels this test uses, as a rough guide, not an official standard.
Other tests
FAQ
Latency vs. ping: what's the difference?
Latency is the delay itself; ping is a common way of measuring it. See the ping test.
Why is my latency fine on a speed test but bad on calls?
Many quick tests report idle latency. Calls happen while other traffic is flowing, so loaded latency matters more.
Does latency affect download speed?
It can. TCP adapts its pace using round trips, so very high latency can make transfers slower to ramp up.