Tuesday, January 27, 2009

The Population of Ancient Rome

In popular books (and far too many scholarly books) is the statement that ancient Rome had a population of 1,000,000 (one million).1 This is likely mistaken for the reasons outlined below.

Map of Ancient Rome

A) Size and situation of Ancient Rome

The Rome described here is the Rome bounded by the Aurelian walls. This Rome covered an area of c. 1,230 hectares2 or c.13.86 sq. km.3 Within the walls of ancient Rome were large areas of dense housing called insulae “apartments” (c. 46,602) and domus “palaces”, (c. 1,760).4 There were also extensive public areas such as the various forums, public buildings, the Imperial palace and gardens and especially near the area of the walls, (which were not built until the reign of the Emperor Aurelian, c. 270 C.E.), large areas of open space.5

B) Population Density of Ancient Rome if Population One Million and Implications

If the Population density of Ancient Rome was 1,000,000, (one million) the following density of population is achieved; a density of c. 813 per hectare or c. 72,150 per sq. km.6

What are the implications of this figure? The most important implication of this figure is that Rome had an incredibly high density of population. Moreover in terms of the actual density of population if we calculate in that a minimum of 25% of the area within the area of the Aurelian walls was public areas, empty space etc., than the population density goes up to c. 1,084 per hectare or c. 96,200 per sq. km. Are these figures realistic?7

The Round Temple in Forum Boarium

C) Comparisons

Some authors have tried to compare ancient Rome with modern cities by citing the incredibly high populations and densities of modern cities. For example:

If we assume a population of about a million, we must conclude that Rome in the early principate was one of the most densely populated cities the world has ever known – as crowded, probably, as modern day Bombay or Calcutta.8

If Bombay and especially Calcutta have become modern day examples of horrific urban congestion the aptness of this comparison is somewhat weakened when the actual population density of Bombay (c. 1980) is found to be c. 18,796 per sq. km., and Calcutta density (c. 1988) is found to be c. 31,779 per sq. km.9

The Colisseum

In fact modern cities seem to have lower population densities than pre-industrial cities because they cover much larger areas. The mean density of a modern city works out to c. 5,991 per sq. km. and median density works out to c. 3,790 per sq. km.10 Regarding a comparison with pre-industrial cities the densities work out to a mean of c. 16,661 per sq. km., and a median of c. 12,897 per sq. km. Regarding figures for cities from the Roman period the mean density works is c. 13,607.11 Of Course given our lack of “hard” information for cities of the Middle ages and the Ancient world the density figures for cities of that time period are not set in stone. The Margin of error is very large.

Another comparison is with the population of modern Rome at various times. In 1901 Rome had an estimated population of c. 538,000 which covered an area of 1,411 hectares with a density of c. 381 per hectare or c. 33,360 per sq. km. And this Rome used far more of the space of ancient Rome for housing.12

Map of Rome in 1902

Finally a comparison with the excavated city sites such as Ostia and Pompeii and the use of modern counting procedures lead to a density of c. 18,000 per sq. km. for Pompeii and c. 32,000 per sq. km. for Ostia. Applying these figures to Rome leads to a population of c. 249,480 if the Pompeii figure is used. If the Ostia figure is used Rome’s population is c. 443,520.13

Temple of Vesta

D) Conclusion

The implications of the above analysis is that a figure for 1,000,000 (one million) for ancient Rome is rather unlikely, given the density called for if the population had been 1,000,000 (one million). Also the fact that Rome would not achieve a population of 1,000,000 (one million) until well into the twentieth century. Further that it is rather unlikely that Rome had such an unprecedented density of population for a pre-industrial city as 72,150 per sq. km.14

Comparison with the ancient excavated cities of Ostia and Pompeii along with comparison with the recent modern population of Rome suggest a figure of 400,000 – 500,000 people for the population of ancient Rome.15

Map of Ancient Rome

1. For example see Daily Life in Ancient Rome: The People and City at the height of the Empire,J. Carcopino, Yale University Press, New Haven, CONN., 1940.

2. The End of the Ancient World and the Beginnings of the Middle Ages, Ferdinand Lot, Harper and Row, New York, 1961, p. 70.

3. The Population of Ancient Rome, Glenn R. Storey, Antiquity, v. 71, 1997, pp. 966-978, p. 966.

4. Footnote 2, at 70.

5. Ibid.

6. See Footnote 3 p. 966, for persons per km. Figure per hectare is my own calculation.

7. Calculations are my own.

8. The Ancient Roman City, J. E., Stambaugh, John Hopkins University Press, Baltimore Maryland, 1988, p. 90.

9. Footnote 3, p. 976.

10. Ibid., p. 975-976.

11. Ibid.

12. Footnote 2, at 70. Calculation of population density per hectare and km. is my own.

13, Footnote 3, pp. 973-975. Calculations of total population are my own.

14 Footnote 3, p. 966.

15. Footnote 3, p. 975, see also Footnote 2.

Pierre Cloutier


  1. Anonymous12:43 pm

    Thank you for this analysis. I'm more in to fiction writing and needed to find a decent population density for a city. I had found an online generator, which seems to be using Ostia's population density.

  2. I am glad you found this article useful. May I ask what fiction you are writing?

  3. 1. They had the ability to support 1 million people.
    2. They supposedly did have 1 million people from censuses.
    3. That is in no way an unprecedented or ridiculous population density, especially if you look at other large ancient cities. Modern urban design often leads to lower population density , not higher. This can be seen in almost every major city, where the area is now much larger, but people are no longer living right on top of each other

  4. The 1 million figure for the population of Rome is little more than a academic urban legend. The bottom line is we don't know what the population of ancient, imperial Rome was and the censuses you refer to say no such thing. They talk about the number of Roman citizens and are then extrapolated to estimate the number of people in Rome. There are no surviving census figures for the net population of Rome.

    The number of cities in either the Ancient or medieval world that had AVERAGE population densities of c. 72,000 per square kilometer was very small. We are being asked to believe that ancient Rome's AVERAGE population density was that of an incredibly crowded city slum. In fact you would have to go to places like the infamous City of Joy slum in Calcutta to find densities like that. Most other Ancient cities on average don't seem to have had anything like this sort of density.

    And of course if this is the AVERAGE density of ancient Rome we have to take into account that c. 20% of the area within the Aurelian walls was unoccupied and that large areas of Rome were occupied by public buildings and the homes of the wealthy. That combined with the fact that AVERAGE densities are just that averages means that most of the population of Rome would be crowded in areas with well above 72,000 people per square kilometer and in fact much of Rome would have areas with densities above 100,000 per square kilometer. This is bluntly absurd. The evidence from Ostia and Pompeii would seem to indicate densities well below that.

    Oh and I agree that modern cities do in fact frequently have AVERAGE densities well below ancient and medieval ones. However the bottom line remains even the most extremely crowded sectors of modern city slums rarely get has crowded has the AVERAGE density of a million person ancient Rome.

    Having been to New York I can say plenty of modern people are living on top of each other.

    I suggest you read Storey's article he is well aware of the fact that some ancient and medieval cities had AVERAGE population densities greater than many modern cities and he takes that into account.

    I am well aware that other historians have critiqued the idea of a "low" population for ancient Rome generally on the basis of citing other equally unreliable figures for the population of ancient and medieval cities.

    All in all the I million figure is simply not worth taking seriously In the slightest. Although the number of Historians who take it seriously is quite amusing.

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