How to Identify a Roman Coin in Six Steps

Short answer: work outside-in. Establish the metal, weight and diameter to get the denomination and period, read the obverse legend to get the ruler, read the reverse type and legend to get the issue, read the exergue to get the mint, then search those elements in a catalogue to get the reference number. Each step narrows the field enough to make the next one manageable.

Identification feels impossible with an unfamiliar coin in your hand and entirely routine once you have a method. The method below is the one specialists use, and it works whether you are holding a crisp denarius or a corroded bronze with three legible letters.

Step 1 — Metal, weight and diameter

Before you read anything, measure. Weigh to 0.01 g and measure the diameter in millimetres. Combined with the metal, those two numbers alone usually give you the denomination, and the denomination gives you a period.

• Silver, 17–20 mm, around 3–4 g — a denarius, so anywhere from the late Republic to the mid 3rd century.
• Silver-ish, 20–24 mm, 2–4.5 g, often with a spiky radiate crown — an antoninianus, so AD 215 onwards.
• Large brassy bronze, 32–35 mm, 21–28 g — a sestertius, so early to mid imperial.
• Small bronze, 15–19 mm, 1.5–3 g — a late Roman AE3 or AE4, so 4th century.
• Gold, 18–20 mm, 7–8 g — an aureus. Gold, 19–21 mm, around 4.5 g — a solidus, so after AD 309.

Weights and diameters here follow Sear (2000) and Kent (1978). One shortcut worth knowing: a radiate crown — a spiked sunburst rather than a laurel wreath — is a denomination marker, not decoration. On silver it marks the antoninianus as a double denarius; on bronze it marks the dupondius against the laureate as.

Step 2 — Read the obverse legend

The obverse normally carries the portrait and a legend running clockwise around the rim, starting near the lower left. It is Latin, heavily abbreviated, and frequently uses ligatures where two letters share a stroke. Do not expect word breaks.

The ruler's name sits inside a scaffold of titles that are largely constant, so learning the scaffold lets you skip straight to the name:

Strip those out and what remains is the name. IMP CAES NER TRAIAN AVG GERM reduces to NER TRAIAN — Trajan. DN CONSTANTIVS PF AVG reduces to Constantius.

Step 3 — Date it from the titles

Two elements turn an identification into a date. TR P with a numeral counts years of tribunician power, renewed annually from the emperor's accession. COS with a numeral counts consulships, held irregularly. Together they usually pin a coin to a single year, and published tables of imperial titulature let you convert them (Casey, 1986).

Victory titles work the same way. A coin of Trajan reading DACICVS must postdate the Dacian wars; one adding PARTHICO must be from the very end of the reign.

Step 4 — Read the reverse

The reverse carries the message, and Roman reverse types form a designed political vocabulary rather than decoration (Howgego, 1995). Most fall into a small number of families, and recognising the family speeds up the search enormously:

• Personifications. A standing figure with attributes: PAX with an olive branch, FORTVNA with a rudder and cornucopia, SALVS feeding a snake, AEQVITAS with scales, VICTORIA winged with a wreath. The legend names her.
• Deities. Jupiter with a thunderbolt, Mars armed, Sol raising his right hand.
• Military types. The emperor on horseback, captives beneath a trophy, legionary standards, FIDES EXERCITVS.
• Vows. VOT V, VOT X MVLT XX and similar inside a wreath, marking vows for an emperor's continued reign at five- and ten-year intervals.
• Buildings and events. Arches, temples, harbours, congiaria, games.

On imperial brass and bronze you will also see a large SC — Senatus Consulto. That is a denomination and authority marker, not part of the reverse legend; we cover what SC means and where it appears separately.

Step 5 — Read the exergue for the mint

The exergue is the segment below the ground line on the reverse. Before roughly the mid 3rd century it is usually blank. From then on it carries a mint mark, and this is where a lot of identifications are actually settled.

A typical late mark has three parts: an optional SM for Sacra Moneta, an abbreviation of the city, and an officina letter naming the workshop. Latin-speaking mints number workshops P, S, T, Q (prima, secunda, tertia, quarta); Greek-speaking mints use A, B, Γ, Δ and so on (Kent, 1978). So SMANTB is the sacred mint of Antioch, second workshop.

Step 6 — Look it up

You now have ruler, denomination, reverse type, reverse legend and mint. That is enough to find the coin in a catalogue.

• OCRE (Online Coins of the Roman Empire) — free, searchable by emperor, denomination, mint and legend, and it returns RIC numbers directly. The best first stop for imperial coins (American Numismatic Society, no date).
• RIC — Roman Imperial Coinage, the standard scholarly catalogue and the numbering everyone quotes (Mattingly et al., 1923–1994).
• RRC — Crawford, for Republican issues, numbered by moneyer (Crawford, 1974).
• RPC — Roman Provincial Coinage, for Greek-language civic issues, which are a separate world (Burnett, Amandry and Ripollès, 1992).
• Sear — Roman Coins and Their Values, more approachable than RIC and organised for collectors (Sear, 2000).
• Auction archives — search the emperor and reverse legend, and you will usually find your exact type described and referenced by someone else.

A worked example

Suppose you have a silver coin, 18 mm, 3.2 g. Silver at that size and weight means denarius. The obverse legend reads IMP CAES M AVR ANTONINVS AVG — strip the titles and you have M AVR ANTONINVS, Caracalla. The reverse shows a standing figure holding scales and a cornucopia with the legend MONETA AVG, so the personification Moneta. The exergue is blank, consistent with an early 3rd century date and the mint of Rome. Search OCRE for Caracalla, denarius, MONETA AVG, and you will land on the RIC number in under a minute.

When the legend is gone

Worn bronzes are the normal case, not the exception, and they are still identifiable. Work from what survives: the denomination from size and weight, the century from the portrait's style and headgear, and the issue from the reverse composition. A late Roman bronze showing a soldier spearing a fallen horseman is the FEL TEMP REPARATIO type of the 350s whether or not a single letter is readable. Two figures holding a standard between them is GLORIA EXERCITVS, from the 330s. The reverse designs are a vocabulary, and learning fifteen of them will identify a large proportion of what you encounter.

Frequently asked questions

Which way round do you read a Roman coin legend?

Almost always clockwise, starting at the bottom left and running up around the rim. The legend usually begins at roughly seven or eight o clock and ends at four or five o clock. A minority of issues, particularly some provincial and late Roman types, read anticlockwise, so if the letters make no sense clockwise, try the other direction.

What do the letters at the bottom of the reverse mean?

That area is called the exergue, and on coins from the late 3rd century onwards it usually carries the mint mark: an abbreviation of the city plus a letter identifying which workshop within the mint struck the coin. SMANT, for example, is Sacra Moneta Antiochiae, the sacred mint of Antioch. Earlier imperial coins generally have no mint mark at all.

Can you date a Roman coin exactly?

Often to within a year, using the titles in the obverse legend. TR P followed by a numeral counts the emperor tribunician years, renewed annually, and COS followed by a numeral counts consulships. An emperor whose coin reads TR P XVIII COS III can usually be placed in a single year of his reign by cross-referencing those numbers.

What if the legend is completely worn away?

You can still narrow it a long way. The metal, weight and diameter give you the denomination and a broad period. The portrait style, the shape of the bust, the crown or radiate diadem, and the reverse subject together usually place a coin within a few decades, and a distinctive reverse type can identify it outright even with no readable letters.

References

• American Numismatic Society (no date) Online Coins of the Roman Empire (OCRE). Available at: http://numismatics.org/ocre/ (Accessed: 26 August 2026).
• Burnett, A., Amandry, M. and Ripollès, P.P. (1992–) Roman Provincial Coinage. London: British Museum Press / Paris: Bibliothèque nationale de France.
• Casey, P.J. (1986) Understanding Ancient Coins: An Introduction for Archaeologists and Historians. London: Batsford.
• Crawford, M.H. (1974) Roman Republican Coinage. Cambridge: Cambridge University Press.
• Howgego, C. (1995) Ancient History from Coins. London: Routledge.
• Kent, J.P.C. (1978) Roman Coins. London: Thames and Hudson.
• Mattingly, H., Sydenham, E.A., Sutherland, C.H.V. and Carson, R.A.G. (eds.) (1923–1994) The Roman Imperial Coinage. 10 vols. London: Spink.
• Sear, D.R. (2000) Roman Coins and Their Values, Volume I: The Republic and the Twelve Caesars, 280 BC–AD 96. London: Spink.
• Sutherland, C.H.V. (1974) Roman Coins. London: Barrie and Jenkins.

Referencing follows the Harvard (author–date) system. Where figures are given as approximate ranges, they are drawn from the works above; published analyses differ by mint, issue and method, and market figures reflect prices observed at the date of writing.