Roman coins came in a variety of denominations, all of which will be unfamiliar to the beginning collector. This page will go over the basic progression of monetary standards from the second century BC to the 5th century AD. Doug Smith's article on the subject ( here and here) has some nice pictures comparing the various sizes.

Republic and Early Empire

Roman coins were minted in many more denominations than the dollars and cents of the United States. To determine which denomination a coin represents, you must look at the metal type, size (diameter, expressed in millimeters), design, and sometimes the weight.

While many denominations were used, accounting was done primarily using the sestertius through late in the third century AD. The sestertius is a large bronze coin very popular with collectors because its size (about 30mm) affords room for more interesting designs. Even though the sestertius was the unit of account, sestertii are not as common as some other denominations, though they are readily available for sale. Collectors with small budgets for coins will be limited to sestertii in rather poor condition.

The most commonly found coin from the second century BC through the first half of the third century AD is the silver denarius. This popular coin is usually between 18 and 20 millimeters across, and weighs between 3 and 4 grams. A denarius was equivalent to four sestertii in the Roman accounting system.

The gold aureus was the most valuable denomination from its inception in 83 BC through the time of Constantine in the early part of the fourth century AD when it was replaced. Valued at 100 sestertii, or 25 denarii, it is about the same size as a denarius, but weighs about twice as much. Most aurei sell for more than one thousand dollars, as they are somewhat rare, and very desirable.

There are three other early imperial period denominations that you are likely to see as a beginning collector. The dupondius was worth half of a sestertius, and was usually made of "orichalcum," a mustard-yellow brass. Starting with the dupondii of the emperor Nero in 64 AD, the denomination can be identified easily by the presence of a "radiate" crown (one with a handful of parallel bars pointing up) on the emperor, or by a crescent moon below the bust of an empress. Dupondii are usually between 25 and 30 mm, and weigh from 11 to 16 grams.

The bronze as was a good sized brass or copper coin, about 23 to 30 mm across, and weighing 8 to 12 grams. Worth one-quarter of a sesterius, it was a commonly used coin amond the Roman public. It was also the unit of account, until the denarius took over that role in the second century BC. The emperor is shown bareheaded or laurate on asses (yes, that's the plural).

Finally, the copper quadrans was the coin with the smallest value in the early part of the Empire. It was worth one-quarter of an as, or one-sixteenth of a sestertius, or one-sixty-fourth of a denarius. I'll let you do the math for the aureus. Quadrantes usually do not show an emperor or empress, and were not minted after 180 AD.

Later Empire

If the information above is a lot to absorb, I regret to say that the situation only gets more confusing with the later Empire. As Rome began to decline in the middle part of the third century, the coinage was changed many times. Since information about some of the new standards are lacking, some later bronze coins are just referred to by their metal type and diameter in mm, as in Æ30. If the number is one through four, then they do not indicate the size in mm, but one of four ranges, as follows: Æ1 (25 mm and larger), Æ2 (21-24 mm), Æ3 (17-20 mm) and Æ4 (under 17mm). But we're getting a bit ahead of the story.

Early in the third century AD, the emperor Caracalla introduced a new denomination, the double-denarius. Collectors usually refer to this an an antoninianus (after Caracalla's family name). Originally it was about 50 percent silver, but after 50 years or so, it had declined to the point where it only contained 2 percent silver, essentially a bronze coin. Like the dupondius, it is recognizeable by the radiate crown or crescent moon. Antoninianii are among the least expensive Roman coins today. They are usually about 20 mm across, and weigh 2.5 to 4 grams.

In 294, Diocletian introduced the mostly bronze follis, which is also known as the nummus. The first folles were over 10 grams, but within about 40 years, they were "reduced" to as little as 1.5 grams.

At this point, the change in Roman bronze coins become more rapid, and one usually sees the Æ1 through 4 notations. You may see a Æ2's referred to as a centenionalis, and a Æ3's as a half-centenionalis. Mid-fourth century bronzes are very common, and among the least expensive Roman coins. They are usually found in the Æ3 and 4 sizes.

Silver and gold coins of the later Empire are quite uncommon and expensive. The aureus was replaced by the solidus in the fourth century, and the denarius was replaced by the siliqua.

As you view and collect Roman coins, all of this will start to make more sense! For now, consult this and other references.

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If you have any questions or comments, please send e-mail to me at .

Last updated June 22, 2006.
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