Marchetti’s Constant

December 15, 2025 10:27 AM Subscribe

Marchetti’s Constant is the idea that throughout human history, from cave dwellers to ancient Greeks to 21st century Londoners, people tend to commute for about an hour a day — 30 minutes out, 30 minutes home. So faster travel leads to longer distances, not less time. (ht: Kevin Kelly, Recomendo)

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Marchett based his work on transportation analyst and engineer, Yacov Zahavi.

"The empirical conclusion reached by Zahavi is that all over the world the mean exposure time for man is around one hour per day. This is a mean over the year and over a population, but the tails of the distribution are not spread much around the central value. The effects of the instinct are pervasive. Even people in prison for a life sentence, having nothing to do and nowhere to go, walk around for one hour a day, in the open. Walking about 5 km/hr, and coming back to the cave for the night, gives a territory radius of about 2.5 km and an area of about 20 km2. This is the definition of the territory of a village, and...this is precisely the mean area associated with Greek villages today, sedimented through centuries of history. The same principle operates when a city, through its importance, political or economic, expands its population and, as a consequence, its physical size. There are no city walls of large, ancient cities (up to 1800), be it Rome or Persepolis, which have a diameter greater than 5 km or a 2.5 km radius. Even Venice today, still a pedestrian city, has exactly 5 km as the maximum dimension of the connected core."

Supercommuting and Marchetti’s Constant is a nuanced look at the implications of the Constant in the modern post-pandemic context, and in the debate over urban sprawl vs densification.