AE1, AE2, AE3 & AE4: Late Roman Bronze Coin Sizes Explained
AE1, AE2, AE3 and AE4 are modern size categories used by numismatists to describe Late Roman copper-alloy coins when the exact ancient denomination name is uncertain. They are not names the Romans used for their coins.
The system is simple in principle: AE1 is the largest category and AE4 the smallest. The exact diameter boundaries can vary slightly between references, so the labels should be treated as practical shorthand rather than rigid ancient denominations.
What Does AE Mean on an Ancient Coin Listing?
AE is a modern numismatic abbreviation derived from Latin aes, a word associated with copper, bronze, or money. In catalog descriptions, AE generally means a copper-alloy coin.
When followed by a number—AE1, AE2, AE3, or AE4—it describes the approximate module or diameter of a Late Roman bronze.
What Are the Common AE1–AE4 Size Ranges?
A widely used approximate system is:
- AE1: over about 25 mm
- AE2: about 21–25 mm
- AE3: about 17–21 mm
- AE4: under about 17 mm
These ranges are conventions, not universally fixed standards. A catalog or reference may draw a boundary slightly differently, especially for coins near the cutoff.
Why Do Collectors Use AE1–AE4?
Late Roman bronze coinage can be difficult to name with certainty. Ancient texts, inscriptions, and later terminology do not give us an unambiguous denomination name for every base-metal issue of the fourth and fifth centuries.
Modern terms such as nummus, follis, centenionalis, and maiorina can be appropriate in particular contexts, but their use is not equally secure for every coin.
AE1–AE4 avoids pretending we know more than we do. It tells the collector the coin’s approximate physical size while leaving the denomination question open.
Are AE1, AE2, AE3 and AE4 Ancient Roman Denominations?
No. A Roman merchant did not ask for an “AE3.” The labels were created by modern numismatists and collectors.
This distinction matters because product listings sometimes make modern shorthand sound like an official ancient denomination. A precise attribution should make clear when a term is modern.
Does a Larger AE Number Mean a Larger Coin?
No—the numbering runs in the opposite direction.
- AE1 is the largest.
- AE2 is smaller.
- AE3 is smaller again.
- AE4 is the smallest category.
Think of the number as a size class rather than a face value.
Does AE1–AE4 Tell You What a Coin Was Worth?
No. The classification describes physical size, not ancient purchasing power or official tariff.
Two coins of similar diameter can belong to different periods, reforms, and monetary systems. Likewise, an AE4 is not automatically worth less to a modern collector than an AE1.
Does Size Determine a Roman Coin’s Collector Value?
No. Size can influence eye appeal, but market value depends more heavily on ruler, rarity, mint, reverse type, condition, portrait style, surfaces, historical importance, provenance, and demand.
A rare AE4 can be worth much more than a common AE1.
Which Late Roman Coins Are Commonly Called AE3 or AE4?
Many fourth-century coins of Constantine I and the Constantinian dynasty fall into AE3 or AE4-sized modules, as do numerous later bronzes of rulers such as Constantius II, Valentinian I, Valens, Gratian, Theodosius I, and their contemporaries.
The exact size of an issue can change over time, and individual flans vary. Always use the ruler, reverse, mint mark, legends, and date alongside diameter.
Why Not Just Call Every Late Roman Bronze a Follis?
Because that can blur several different monetary systems together.
The large silvered copper coin introduced in Diocletian’s reform around AD 294 is conventionally called a nummus or follis. Its descendants were repeatedly reduced and reorganized, but applying “follis” indiscriminately to every small fourth- or fifth-century bronze can imply a certainty the evidence does not support.
AE1–AE4 is useful precisely because it can describe size without forcing a disputed denomination name.
How Should You Attribute an AE Coin?
Use the AE class only as one part of the attribution. Check:
- Emperor or issuing authority
- Obverse legend and portrait
- Reverse type and legend
- Mint mark and officina
- Diameter and weight
- Date range
- Standard catalog reference when available
A coin described simply as “Roman AE3” is only partially attributed.
Frequently Asked Questions
What does AE3 mean?
AE3 is a modern numismatic size category generally used for Late Roman copper-alloy coins around 17–21 mm in diameter, depending on the reference.
What does AE4 mean?
AE4 generally describes the smallest Late Roman bronze size class, usually under about 17 mm.
Is AE the same as bronze?
In catalog usage, AE broadly indicates copper-alloy coinage. Ancient “bronze” compositions vary, so the abbreviation is intentionally general.
Why do different dealers classify the same-sized coin differently?
Because the size boundaries are modern conventions and are not completely standardized. Coins near a cutoff can reasonably be described differently by different references.
Are AE3 and AE4 coins good for beginners?
Yes. Many are affordable and teach important skills such as reading mint marks, recognizing emperors, identifying reverse types, and understanding the uncertainty of Late Roman denomination names.
Final Thought
AE1–AE4 is useful because it is modest. It tells you how large a Late Roman bronze is without pretending to solve every question about what Romans called the denomination.
For a collector, that makes the system a practical first step—not a complete attribution.