How many people lived in the Roman Empire?

The best estimate

No Roman ever counted everyone in the empire, so every total is a modern estimate. The classic one comes from the German historian Karl Julius Beloch, who in 1886 put the population at the death of Augustus, in AD 14, at about 54 million. Most historians today land nearby: some 60 million when Trajan’s empire was at its widest in AD 117, and perhaps 70 to 75 million at the peak, before the plague of 165. That was between a sixth and a quarter of all the people on Earth.

What Rome counted

Rome did count its citizens. Every few years censors registered each citizen and his property, to sort Romans for voting, taxes and the army. Augustus lists three of his counts in his own record of his reign, the Res Gestae:

• 28 BC: 4,063,000 Roman citizens.
• 8 BC: 4,233,000.
• AD 14: 4,937,000.

Those figures cover citizens only, at a time when most people in the provinces were not citizens. Historians also argue about whom they include: everyone, women and children too, or only adult men, as earlier counts had. The answer moves Italy’s population by millions. Citizen and subject came to mean nearly the same thing only in AD 212, when Caracalla made almost every free person a citizen.

Counting the provinces

Provinces were counted too, for taxes. Luke dates the birth of Jesus by one such count:

Now in those days, a decree went out from Caesar Augustus that all the world should be enrolled. This was the first enrollment made when Quirinius was governor of Syria. All went to enroll themselves, everyone to his own city.

Historians know of no single census of the whole empire under Augustus, and Josephus dates Quirinius’s census of Judaea to AD 6, a puzzle for the year of Jesus’s birth. Local counts were real, though. In Egypt every household filed a return every fourteen years, and about three hundred survive on papyrus. From them scholars have rebuilt the ages and families of a whole province. Life expectancy at birth there was only about 22 to 25 years, mostly because so many babies died.

Where they lived

Rome itself was the giant: a city of perhaps a million people, a size no European city reached again until the 1800s. Feeding it took grain fleets from Egypt and North Africa, free grain for some 200,000 citizens and, in time, eleven aqueducts. Alexandria may have had half a million. Yet most Romans never lived in a city. Archaeologists have identified some 1,400 Roman towns, most with about 5,000 people, and at least three Romans in four lived in the countryside.

Rome’s one rival in size lay at the other end of Asia. Han China took a census in AD 2 and recorded 57,671,400 people in 12,366,470 households. The two empires, which knew each other only by rumor and silk, were roughly the same size.