Sizes of Coins (comparisons)

Coins in this website are shown in millimeter (mm) sizes and are approximate because of the irregularity of ancient coins. The ancient coins shown below are only samples of some denominations, and not all of those types of denominations will have the same (mm) dimensions.

To give you an idea of what size a mm is, think of the following familiar items that you have available.

U.S. Currency

U.S. dimes are 18 mm in diameter


Roman Denarius


U.S. pennies are 19 mm in diameter


Greek Drachma


U.S. nickels are 21 mm in diameter


Parthian Drachma


U.S. quarters are 24 mm in diameter


Greek Stater


U.S. Silver Dollars are about 39 mm in diameter.


Greek Tetradrachma


Compare these U.S. coin sizes in mm's to the coins you see listed throughout the website. Measurements of listed coins are the width of the coin, and include the frame of the coin if in jewelry form.