Title: Demography of the Roman Empire
Content:   Demographically, as in other more recent and thus better documented pre-modern societies, papyrus evidence from Roman Egypt suggests the demographic profile of the Roman Empire had high infant mortality, a low marriage age, and high fertility within marriage. Perhaps half of the Roman subjects died by the age of 5. Of those still alive at age 10, half would die by the age of 50. During the 1st and 2nd centuries, the Roman Empire had a population estimated in the range of 58 to 76 million. The population likely peaked just before the Antonine Plague, Harper provides an estimate of a population of 75 million and a population density of about 20 people per square kilometer during its peak. In contrast to other ancient and medieval societies, the Roman Empire appears to have had unusually high urbanization rates. During the 1st and 2nd centuries CE, the population of the city of Rome is conventionally estimated at one million inhabitants, Ian Morris estimated that no other city in Western Eurasia would have as many again until the 19th century.
Title: Demography of the Roman Empire
Content:  Beloch's 1886 estimate for the population of the empire during the reign of Augustus: Russell's 1958 estimate for the population of the empire in 350 CE: Recent demographic studies have argued for a population peak ranging from 70 million (comparable to the contemporaneous and similarly sized Han empire in China), with one-tenth of them located in Italy itself, to more than 100 million.
Title: Demography of the Roman Empire
Content:  By the standards of pre-modern economies, the Roman Empire was highly urbanized. According to recent work, there are at least 1,388 identified urban sites in the Roman world dated from the Late Republican and Early Imperial period. At its peak, the city of Rome had at least one million inhabitants, a total not equaled again in Europe until the 19th century. As the imperial capital, Rome was sustained by transfers in kind from throughout the empire; no other city could be sustained at this level. The other major cities in the empire (Alexandria, Antioch, Carthage, Ephesus, Salona etc.) had populations of over a hundred thousand, 
Title: Classical demography
Content:  There are many estimates of the population for the Roman Empire, that range from 45 million to 120 million with 55–65 million as the most accepted range. An estimated population of the empire during the reign of Augustus: Beloch's 1886 estimate for the population of the empire during the reign of Augustus: Russell's 1958 estimate for the population of the empire in 1 AD: Russell's 1958 estimate for the population of the empire in 350 AD:
Title: Rome
Content:  middle of the fifth century it seems that Rome continued to be the most populous city of the two parts of the Empire. According to Krautheimer it was still close to 800,000 in 400 AD; had declined to 500,000 by 452, and dwindled to perhaps 100,000 in 500 AD. After the Gothic Wars, 535–552, the population may have dwindled temporarily to 30,000. During the pontificate of Pope Gregory I (590–604), it may have reached 90,000, augmented by refugees. Lancon estimates 500,000 based on the number of 'incisi' enrolled as eligible to receive bread, oil and wine rations; the number fell 
Title: Roman Empire
Content:  it the largest population of any unified political entity in the West until the mid-19th century. Recent demographic studies have argued for a population peak ranging from 70 million to more than 100 million. Each of the three largest cities in the Empire – Rome, Alexandria, and Antioch – was almost twice the size of any European city at the beginning of the 17th century. As the historian Christopher Kelly has described it: "Then the empire stretched from Hadrian's Wall in drizzle-soaked northern England to the sun-baked banks of the Euphrates in Syria; from the great Rhine–Danube river system, which snaked across the 
Title: Military of ancient Rome
Content:  At its territorial height, the Roman Empire may have contained between 45 million and 120 million people. Historian Edward Gibbon estimated that the size of the Roman army "most probably formed a standing force of three hundred and seventy-five thousand men" at the empire's territorial peak in the time of the Roman emperor Hadrian (117 − 138C). This estimate probably included only legionary and auxiliary troops of the Roman army. However, Gibbon states that it is "not... easy to define the size of the Roman military with any tolerable accuracy". In the late imperial period, when vast numbers of foederati were employed by the Romans, Antonio Santosuosso estimated the combined number of men in arms of the two Roman empires numbered closer to 700,000 in total (not all members of a standing army), drawing on data from the Notitia Dignitatum. However, he notes that these figures were probably subject to inflation due to the practice of leaving dead soldiers "on the books" to continue to draw their wages and ration. Furthermore, it is irrespective of whether the troops were raised by the Romans or simply hired by them to fight on their behalf.
Title: Demography of the Roman Empire
Content:  produced population densities not otherwise achieved in those areas until the 20th century. Bruce Frier, in a recent estimate of the population of the empire, suggested a figure of 12 million as "considerably more plausible". Beloch's figures for Spain and Africa have also been revised downwards. In a more recent publication, Kyle Harper suggests 75 million for the empire as a whole with 16 million for Anatolia and Greater Syria. This estimate produces a population density of ca. 20 inhabitants per square kilometer a low figure by modern standards (the United Kingdom, for example, has a population density of 254.7/km2). The population density in the Greek East was 24/km2, denser than the 
Title: Demography of the Roman Empire
Content:  West at 17/km2; only the Western provinces of Italy and Sicily had a density higher than the average of the East. Harper estimates the population at the time of Augustus at 60 million, a discrepancy of 10% from Beloch's 1886 estimate, and suggests a population growth rate of 0.1% per year, reaching 75 million after nearly two centuries of growth. Current estimates suggest that slaves constituted about 15 percent of the Empire's total population; the proportionate figure would be much higher in Italy and much lower in Africa and Egypt. Bruce Frier's estimate produces a population density of 13.6 inhabitants per square kilometer. The population density in the Greek East was 20.9/km2, 
Title: Demography of the Roman Empire
Content:  Modern estimates of the population of the Roman Empire started with the fundamental work of 19th-century historian Karl Julius Beloch. His estimates of the area of different components of the empire, based on planimetric estimates by contemporary military cartographers, have not been challenged by any more modern analyst. By providing a check to population densities, these area figures compel a baseline level of plausibility. Beloch's 1886 estimate of the population of the empire in 14 CE has withstood contemporary and more recent criticism, and underlies modern analysis (his 1899 revision of those figures is less esteemed). Only his estimates for Anatolia and Greater Syria required extensive revision; Beloch estimated population figure, 19 

Question: what was the population of the roman empire at its height?
Answer: 50 to 90 million inhabitants.
70 million.
55–60 million.
an estimated 70 million people.