ONE-WAY TRAVEL TIME
about 200,000 km/s in fiber
299,792 km/s in vacuum
The time for light to travel one way along the great-circle path between two points, at fiber speed.
What this measures
LATENCY MAP divides the great-circle distance between two points by the speed of light in fiber. The result is one-way travel time. It is the shortest surface path on a sphere, not a cable route.
That number is a physical lower bound for a signal in fiber along that path. Planning a CDN, a multi-region service, a game server, or a link between cities starts from this bound. The network you actually build will be slower.
How the number is made
TRAVEL TIME = DISTANCE / 200,000 km/s
Example: New York to London
Distance: 5,570 km, great-circle
Speed in fiber: 200,000 km/s
One-way travel time: 5,570 / 200,000 = 27.85 ms
Click two points on the map. Each completed pair keeps its distance and one-way travel time. The fiber speed used here is vacuum speed divided by a refractive index of about 1.5.
Why a real path is slower
The map does not include:
- Cable routes that leave the great circle, including undersea paths
- Time spent in routers, switches, and other equipment
- Protocol overhead and queuing
Distance uses the haversine formula on a sphere of radius 6,371 km.
Measure a path
Place two points and read the one-way travel time.
OPEN MAP