Fibre Latency Calculator for European Data Centres
Minimum round-trip and one-way delay in optical fibre between 20 European data-centre hubs, from Frankfurt and London to Madrid and Helsinki, with the physics shown.
What is the lowest latency physics allows between Frankfurt and London, or Dublin and Milan? Light in optical fibre covers about 204,000 km per second, so distance alone sets a floor no network can beat. Pick two hubs to see that floor, and adjust the route factor to allow for real cable paths.
Fibre latency between European data-centre hubs
- Light in standard single-mode fibre travels at about 204,107 km/s, so every 1,000 km of fibre adds at least 4.90 ms one way and 9.80 ms to a round trip.
- Among these 20 hubs the shortest straight-line round trip is Amsterdam to Brussels, 1.7 ms; the longest is Helsinki to Lisbon, 32.9 ms.
Minimum round trip between hubs, milliseconds
| From \ to | Amsterdam | Berlin | Brussels | Copenhagen | Dublin | Frankfurt | Helsinki | Lisbon | London | Madrid | Marseille | Milan | Munich | Oslo | Paris | Prague | Stockholm | Vienna | Warsaw | Zurich |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Amsterdam | – | 5.6 | 1.7 | 6.1 | 7.4 | 3.6 | 14.7 | 18.3 | 3.5 | 14.5 | 9.9 | 8.1 | 6.5 | 8.9 | 4.2 | 7.0 | 11.0 | 9.2 | 10.7 | 6.0 |
| Berlin | 5.6 | – | 6.4 | 3.5 | 12.9 | 4.1 | 10.8 | 22.7 | 9.1 | 18.3 | 11.6 | 8.2 | 4.9 | 8.2 | 8.6 | 2.7 | 8.0 | 5.1 | 5.1 | 6.5 |
| Brussels | 1.7 | 6.4 | – | 7.5 | 7.6 | 3.1 | 16.1 | 16.8 | 3.1 | 12.9 | 8.3 | 6.8 | 5.9 | 10.6 | 2.6 | 7.0 | 12.5 | 9.0 | 11.4 | 4.8 |
| Copenhagen | 6.1 | 3.5 | 7.5 | – | 12.1 | 6.6 | 8.7 | 24.3 | 9.4 | 20.3 | 14.4 | 11.4 | 8.2 | 4.7 | 10.1 | 6.2 | 5.1 | 8.5 | 6.6 | 9.4 |
| Dublin | 7.4 | 12.9 | 7.6 | 12.1 | – | 10.7 | 19.8 | 16.1 | 4.5 | 14.2 | 13.8 | 13.9 | 13.5 | 12.4 | 7.7 | 14.3 | 16.0 | 16.5 | 17.9 | 12.1 |
| Frankfurt | 3.6 | 4.1 | 3.1 | 6.6 | 10.7 | – | 14.8 | 18.5 | 6.2 | 14.2 | 7.8 | 5.1 | 3.0 | 10.8 | 4.7 | 4.0 | 11.6 | 5.9 | 8.7 | 3.0 |
| Helsinki | 14.7 | 10.8 | 16.1 | 8.7 | 19.8 | 14.8 | – | 32.9 | 17.8 | 28.9 | 22.4 | 19.0 | 15.6 | 7.7 | 18.7 | 12.8 | 3.9 | 14.1 | 9.0 | 17.4 |
| Lisbon | 18.3 | 22.7 | 16.8 | 24.3 | 16.1 | 18.5 | 32.9 | – | 15.5 | 4.9 | 12.9 | 16.5 | 19.3 | 26.8 | 14.2 | 22.0 | 29.3 | 22.5 | 27.0 | 16.9 |
| London | 3.5 | 9.1 | 3.1 | 9.4 | 4.5 | 6.2 | 17.8 | 15.5 | – | 12.4 | 9.8 | 9.4 | 9.0 | 11.3 | 3.4 | 10.1 | 14.0 | 12.1 | 14.2 | 7.6 |
| Madrid | 14.5 | 18.3 | 12.9 | 20.3 | 14.2 | 14.2 | 28.9 | 4.9 | 12.4 | – | 8.0 | 11.6 | 14.5 | 23.4 | 10.3 | 17.4 | 25.4 | 17.7 | 22.4 | 12.2 |
| Marseille | 9.9 | 11.6 | 8.3 | 14.4 | 13.8 | 7.8 | 22.4 | 12.9 | 9.8 | 8.0 | – | 3.8 | 7.1 | 18.5 | 6.5 | 10.0 | 19.4 | 9.9 | 15.0 | 5.1 |
| Milan | 8.1 | 8.2 | 6.8 | 11.4 | 13.9 | 5.1 | 19.0 | 16.5 | 9.4 | 11.6 | 3.8 | – | 3.4 | 15.8 | 6.3 | 6.3 | 16.2 | 6.1 | 11.2 | 2.1 |
| Munich | 6.5 | 4.9 | 5.9 | 8.2 | 13.5 | 3.0 | 15.6 | 19.3 | 9.0 | 14.5 | 7.1 | 3.4 | – | 12.8 | 6.7 | 2.9 | 12.9 | 3.5 | 7.9 | 2.4 |
| Oslo | 8.9 | 8.2 | 10.6 | 4.7 | 12.4 | 10.8 | 7.7 | 26.8 | 11.3 | 23.4 | 18.5 | 15.8 | 12.8 | – | 13.1 | 10.9 | 4.1 | 13.2 | 10.4 | 13.7 |
| Paris | 4.2 | 8.6 | 2.6 | 10.1 | 7.7 | 4.7 | 18.7 | 14.2 | 3.4 | 10.3 | 6.5 | 6.3 | 6.7 | 13.1 | – | 8.6 | 15.1 | 10.1 | 13.4 | 4.8 |
| Prague | 7.0 | 2.7 | 7.0 | 6.2 | 14.3 | 4.0 | 12.8 | 22.0 | 10.1 | 17.4 | 10.0 | 6.3 | 2.9 | 10.9 | 8.6 | – | 10.3 | 2.5 | 5.1 | 5.2 |
| Stockholm | 11.0 | 8.0 | 12.5 | 5.1 | 16.0 | 11.6 | 3.9 | 29.3 | 14.0 | 25.4 | 19.4 | 16.2 | 12.9 | 4.1 | 15.1 | 10.3 | – | 12.2 | 7.9 | 14.4 |
| Vienna | 9.2 | 5.1 | 9.0 | 8.5 | 16.5 | 5.9 | 14.1 | 22.5 | 12.1 | 17.7 | 9.9 | 6.1 | 3.5 | 13.2 | 10.1 | 2.5 | 12.2 | – | 5.4 | 5.8 |
| Warsaw | 10.7 | 5.1 | 11.4 | 6.6 | 17.9 | 8.7 | 9.0 | 27.0 | 14.2 | 22.4 | 15.0 | 11.2 | 7.9 | 10.4 | 13.4 | 5.1 | 7.9 | 5.4 | – | 10.2 |
| Zurich | 6.0 | 6.5 | 4.8 | 9.4 | 12.1 | 3.0 | 17.4 | 16.9 | 7.6 | 12.2 | 5.1 | 2.1 | 2.4 | 13.7 | 4.8 | 5.2 | 14.4 | 5.8 | 10.2 | – |
Straight-line fibre between city centres, route factor 1. Real routes are longer, so measured round trips are higher.
Round trips along mapped fibre routes, milliseconds
| From \ to | Amsterdam | Berlin | Brussels | Copenhagen | Dublin | Frankfurt | Helsinki | Lisbon | London | Madrid | Marseille | Milan | Munich | Oslo | Paris | Prague | Stockholm | Vienna | Warsaw | Zurich |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Amsterdam | – | 6.4 | 1.8 | 6.8 | – | 3.8 | – | 20.1 | – | 15.7 | 11.4 | 9.2 | 7.2 | 11.6 | 4.4 | 8.1 | 12.4 | 10.8 | 11.9 | 7.0 |
| Berlin | 6.4 | – | 7.1 | 3.9 | – | 4.7 | – | 25.4 | – | 20.9 | 13.4 | 9.5 | 5.4 | 8.8 | 9.7 | 3.1 | 9.5 | 5.9 | 5.6 | 7.7 |
| Brussels | 1.8 | 7.1 | – | 8.5 | – | 3.5 | – | 18.5 | – | 14.1 | 9.8 | 8.9 | 6.8 | 13.4 | 2.8 | 7.8 | 14.1 | 10.5 | 12.4 | 6.7 |
| Copenhagen | 6.8 | 3.9 | 8.5 | – | – | 7.1 | – | 26.8 | – | 22.4 | 15.8 | 12.7 | 9.2 | 4.9 | 11.1 | 7.0 | 5.6 | 9.7 | 8.9 | 10.5 |
| Dublin | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – |
| Frankfurt | 3.8 | 4.7 | 3.5 | 7.1 | – | – | – | 21.2 | – | 16.8 | 8.8 | 5.6 | 3.3 | 11.9 | 5.9 | 4.4 | 12.7 | 7.0 | 9.5 | 3.4 |
| Helsinki | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – |
| Lisbon | 20.1 | 25.4 | 18.5 | 26.8 | – | 21.2 | – | – | – | 5.2 | 15.5 | 19.7 | 21.8 | 31.7 | 15.7 | 24.6 | 32.4 | 25.0 | 30.7 | 18.8 |
| London | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – |
| Madrid | 15.7 | 20.9 | 14.1 | 22.4 | – | 16.8 | – | 5.2 | – | – | 10.3 | 14.5 | 17.3 | 27.3 | 11.3 | 20.1 | 28.0 | 20.6 | 26.2 | 14.3 |
| Marseille | 11.4 | 13.4 | 9.8 | 15.8 | – | 8.8 | – | 15.5 | – | 10.3 | – | 4.3 | 8.4 | 20.7 | 7.0 | 11.8 | 21.4 | 11.0 | 17.4 | 6.3 |
| Milan | 9.2 | 9.5 | 8.9 | 12.7 | – | 5.6 | – | 19.7 | – | 14.5 | 4.3 | – | 4.1 | 17.5 | 8.0 | 7.5 | 18.3 | 6.7 | 13.1 | 2.2 |
| Munich | 7.2 | 5.4 | 6.8 | 9.2 | – | 3.3 | – | 21.8 | – | 17.3 | 8.4 | 4.1 | – | 14.1 | 7.0 | 3.5 | 14.8 | 3.8 | 10.0 | 3.0 |
| Oslo | 11.6 | 8.8 | 13.4 | 4.9 | – | 11.9 | – | 31.7 | – | 27.3 | 20.7 | 17.5 | 14.1 | – | 16.0 | 11.9 | 4.3 | 14.6 | 13.8 | 15.3 |
| Paris | 4.4 | 9.7 | 2.8 | 11.1 | – | 5.9 | – | 15.7 | – | 11.3 | 7.0 | 8.0 | 7.0 | 16.0 | – | 9.2 | 16.7 | 10.8 | 15.1 | 5.9 |
| Prague | 8.1 | 3.1 | 7.8 | 7.0 | – | 4.4 | – | 24.6 | – | 20.1 | 11.8 | 7.5 | 3.5 | 11.9 | 9.2 | – | 12.6 | 2.8 | 6.7 | 6.1 |
| Stockholm | 12.4 | 9.5 | 14.1 | 5.6 | – | 12.7 | – | 32.4 | – | 28.0 | 21.4 | 18.3 | 14.8 | 4.3 | 16.7 | 12.6 | – | 15.3 | – | 16.1 |
| Vienna | 10.8 | 5.9 | 10.5 | 9.7 | – | 7.0 | – | 25.0 | – | 20.6 | 11.0 | 6.7 | 3.8 | 14.6 | 10.8 | 2.8 | 15.3 | – | 6.4 | 6.2 |
| Warsaw | 11.9 | 5.6 | 12.4 | 8.9 | – | 9.5 | – | 30.7 | – | 26.2 | 17.4 | 13.1 | 10.0 | 13.8 | 15.1 | 6.7 | – | 6.4 | – | 12.2 |
| Zurich | 7.0 | 7.7 | 6.7 | 10.5 | – | 3.4 | – | 18.8 | – | 14.3 | 6.3 | 2.2 | 3.0 | 15.3 | 5.9 | 6.1 | 16.1 | 6.2 | 12.2 | – |
Shortest mapped route along land fibre, 135 of 190 pairs. A dash means there is no mapped land route: those pairs, London, Dublin and some Baltic links, rely on submarine cables.
Method
Distance is measured between city centres. Delay is the fibre path divided by the speed of light in single-mode fibre, about 204,000 km/s; the path is the straight line times the route factor, or the mapped route. It is a physical lower bound: real routes and equipment add delay.
ScienceShot calculation. How we build it: Method and standards.