I was trying to compare the military spending of the Roman empire in the 1st century with modern military spending and how much of a burden that was to Roman people. The Wikipedia page of the economics of the Roman army states that the military spending was about 2.5% of the Empire GDP.

That lead me to search for the figures estimated for the GDP of the 1st c. Roman empire. I noticed that the government spending was very low compared to modern spending. For example, this paper estimates the GDP and states that the government spending was about 5% of the total GDP. Comparing that to the US now with about 40% of GDP as government spending, the difference is very obvious.

So my question here is why weren't the Roman empire able to maintain a government spending level similar to modern governments ?

  • 2
    Primitive governments were less effective at generating tax revenues, and generally had less things to spend on.
    – Semaphore
    Commented Feb 23, 2015 at 0:20
  • 3
    1) Workers were way less productive, so there far less goods to get from them without putting them in the brink of starvation, 2) Administration and tax recolection was a lot more inefficient, requiring "middle men" which took their cut and 3) the state provided only the most basic services (i.e., Army)
    – SJuan76
    Commented Feb 23, 2015 at 0:30
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    (1) The government provided fewer services, (2) government services were provided by individuals rather than the government at their own expense (3) Many large capital expenditures were paid for by conquest. (4) It makes no sense to compare the government expenditures of a modern socialist democracy to the capital expenditure of any of the different types of government practiced by the Romans.
    – MCW
    Commented Feb 23, 2015 at 14:15
  • 1) The bulk of the population had to farm. 2) the bulk of the revenue needed to go to defense spending on soldiers and installations. 3) Moving anything about - even cash - was expensive. 4) Communication was slow to impossible. Therefore it is best to push most things down to a local level and only use the central government for emergencies.
    – Oldcat
    Commented Feb 24, 2015 at 1:10
  • @Oldcat, I don't understand what you mean by "revenue" here, but the bulk of the GDP didn't go to defense spending, that's the whole point of this question. The defense spending was only 2.5% of the GDP and it is already included in the government spending which was 5% of the GDP. But other than that, I agree with you. Commented Feb 24, 2015 at 19:51

3 Answers 3


First of all, I would not trust Wikipedia numbers about Roman Empire. Roman empire existed for 4 centuries, and the things did not stay unchanged. Second, we have no reliable statistics for most periods. Even the population of the Empire in various periods is not clear, and estimates widely vary. Third, you cannot compare ancient economy with modern economy, it is simply ridiculous. Some portion of the Roman economy was based on slave labor, for example. And again, we do not know what portion, and how many slaves there were. Slaves did not pay tax. Fourth, most European countries nowadays spend less than 2.5% of their GDP on their military. Including NATO members. Fifth: the government funds in the Roman empire were not only spend on the army; they did huge construction works everywhere in Europe (which you can see even now), then in various periods the population of Rome itself not only did not pay taxes but was supported at the government expense.

With all this, it is of course true that ancient societies could not spend as large part of GDP on government expenses as modern ones, simply because the labor productivity is incomparable. For most of the history most people worked just for subsistence. It is only surplus production besides the subsistence, which can be used on all other expenses, including military.

And you don't have to use the Roman empire for comparison. Compare the part of GDP which was collected in taxes in the late 19-th century US with the modern numbers:-)

  • I'm guessing, but imagine a Roman legion with equipment cost less, relatively, than one single modern jet fighter and trained crew!
    – TheHonRose
    Commented Feb 24, 2015 at 2:59
  • 1
    What are you talking about? How do you compare costs?? No meaningful comparison can be made.
    – Alex
    Commented Feb 24, 2015 at 4:03
  • @TheHonRose: The comparison, traditionally, is made in terms of firepower. Hence, one tank is equal to about 30 modern infantry. I'm not sure how you would compare them to Roman phalanx, but would start with soldiers needed to hold a certain territory.
    – Carmi
    Commented Feb 25, 2015 at 19:43
  • We were talking of comparison of cost, not firepower. What do you take for comparison? The price of gold? Bronze? Bread? Oil? Fish? Energy? :-)
    – Alex
    Commented Feb 25, 2015 at 19:56
  • I'm no military historian, so out of my depths, but would suggest that the more complex the "technology" the greater the investment required?
    – TheHonRose
    Commented Feb 25, 2015 at 23:23

While I agree with the other answer givers that you're unlikely to find reliable information on Roman imperial spending budgets, I think we can usefully work back from modern spending figures to show the disparity.

For example, below are some of the major spending areas of the United States budget, and a note about Roman equivalence:

  1. Social Security is a huge portion of US federal spending ( about 20%). The Romans had no state care for the elderly, who would have lived with family.
  2. State funded healthcare (Medicare and Medicaid, as well as emergency room treatments) are another 20% of the budget, and didn't exist in Roman times.
  3. Public Works and infrastructure is about 4% of US federal government spending, but there's more money supplied by the individual states. This is probably about equivalent to the Romans, who built roads, aqueducts, public baths and more in most of the empire.
  4. Defence spending is about 25% of the US federal budget, and was a much smaller component of the Roman budget. However, I'm not sure the militaries are comparable. Obviously, the Romans didn't have to pay for the upkeep of a nuclear arsenal, submarines or an airforce, which are all incredibly expensive in terms of equipment costs. Additionally, Roman soldiers were paid partially in spoils of war, which were also a form of income for the empire. Obviously, this isn't something the US government does.

Anyway, that was a quick comparison to the US. Note that even in modern times, the US spends more on defence than the next 26 countries combined. So perhaps the defence budget of the UK, France or Australia is more comparable to Roman numbers.

Addition: I have now looked up the UK's 2014 budget figures, and defence spending is on the order of 5% of spending, which probably puts it at about 2% of GDP.


The methodological caveats listed by @Alex are all true. I'd also add that there was no notion of state credit so everything had to be financed out of revenues. And of course, the very notion of what government is responsible for was quite different in antiquity - the ancients were very far from the idea of a welfare state. Perhaps early 19th century England or France would be a better model for comparison.

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