Long-distance Cable Costs

Ever wonder how much a long-distance cable costs? Apparently, the costs to rent a slice of a long-distance cable from AT&T or MCI are quite high. A 1000km OC-3 (150Mbps) link may cost in the neighborhood of $1,000,000 per year, for terrestrial cables. I would guess that undersea cables are much more expensive to rent.

But how much does it cost AT&T to install one of these cables?

Undersea Cables

This table lists some undersea cables, their speed, estimated total cost, cost per km, and cost per megabit.



Length (km)

Project Cost



TAT-9 565Mbps 9,310 $450M $48,355 $85,548 March, 1992
TPC-4 560Mbps 9,860 $373M $37,830 $67,553 Oct., 1992
CIOS 622Mbps 261 $10M $38,314 $61,598 late 1993
TPC-5 5Gbps (max 20) 25,000 $1.12B $44,800 $8,960 late 1996
FLAG 10Gbps 27,000 $1500M $56,000 $5,600 1997?
Columbus III 10Gbps 11,000 $300M $27,000 $2,700 July, 1999
My source for this data is primarily press reports on the web from the companies laying the cables (primarily AT&T). Click on the cable names in the first column to see the press reports.


The short answer is that undersea cable costs about $50,000 per km to install, independent of the speed of the cable. In the last 5 years, there is a very clear trend. The cost per gigabit has steadily dropped, and is now a factor of 10-20 less than what it was in 1992. This cost reduction appears entirely due to the huge increase in cable bandwidths.

More info

See the AT&T Technical Journal Volume 74, No. 1 (Jan / Feb, 1995) for an interesting issue about undersea cables.

Also, visit the International Cable Protection Committee for a list of all undersea cables.

Wired magazine had a fascinating article in early 1997 by Neal Stephenson about laying the FLAG cable. I don't have the exact link to it, but a net search should turn it up.

Hugh Holbrook - holbrook .at. dsg .dot. stanford .dot. edu