16 cities · 608 cables · 4 maps

Cable Latency Survey

Measured round-trip times between cities, against the minimum time light needs along each map's cable routes.

01Ping

Servers in 16 cities ping each other, 16 packets, twice. The fastest reply counts.

02Route

Each pair is routed over the in-service submarine cables and straight land links, separately on each map.

03Compare

A reply faster than light in glass along a map's route rules that map out for that pair.

Results by map

Speed limits

Light in a vacuum travels 299,792 km/s. In standard single-mode fibre (group index 1.468) it travels 204,190 km/s. Every submarine cable is fibre, so the minimum round trip is 2 × route length ÷ 204,190 km/s. That floor sets each bar and the speed of the gold pulses on the map.

Measured times sit above the floor: installed cable is longer than its drawn route, and routers and queues add delay. A time above the floor proves nothing. A time below it means the map puts the cities too far apart.

Light in a vacuum is 47% faster than light in fibre; radio through air is within 0.03% of it. A time below the vacuum floor is impossible for any cable, radio link or satellite.

Map key
Cyan route: the reply came back after light in glass could have made the trip. Possible on that map.
Orange route: the reply beat light in glass along that map's route. Impossible on that map, because every cable is glass.
Red route: the reply beat light in a vacuum along that map's route. Impossible for anything: cable, radio or satellite.
White line: the route you selected.
Gold pulse: light in glass running that map's route and back, at 204,190 km/s, shown 24× slower.
Ring at the start city: the real reply arriving, in the route's colour. An orange or red ring that fires while the pulse is still out on the route is a reply that beat light.

Speed each live route would need

How each map measures distance

Every measurement

Log scales, milliseconds. Small dots: WonderNetwork's public 2020 ping set. Large dots: the live grid.

Cable crossings

RIPE Atlas anchor-to-anchor traceroutes. The jump in round-trip time at the sea-crossing hop is the cable itself, compared with light along that cable's drawn route.

Bars: light in glass along the cable's route, there and back. White line: the measured jump, fastest of a day of traceroutes every 15 minutes. Click a crossing to see the route on the map.

Check your own ping

Ping a server from your computer and enter the lowest time. Local network and ISP delay only add time.


  






  
Method and data

  
How the routes are built

  
Data sources

  
Stricter and looser versions

  
Every live measurement