Why are coins historically round and not square?

We can find quite a few reasons for the roundness of coins–these relate to different time periods, but interestingly there are actually several examples of square-shaped coins. However, the round coin is definitely more common no matter what country and history we’re talking about.

The most obvious reason for coins being round is their ease of use, so to say. It is easy to pick up round coins and scoop them up, put them into tightly packed bags, etc, without any worry of corners causing issues. We can also stack up the coins and wrap them up in rolls without worrying about any corners tearing at the package.

Then there’s the fact that coins are intended to be hard-wearing and semi-permanent. Currently, there are several coins still in circulation that are likely older than you or me. This is mostly because of their round shape, which is less likely to wear down unevenly. With a circular shape, no one part of it sticks out further than the rest from any angle, so there’s little chance of any part wearing down. The numbers and imprints might be smoothed out over time, but it would require some very hard usage to erase them completely.

A historical reason for the roundness is that a lot of coins were made by pressing down a small ingot with a pre-made stamp. We can observe a similar process in the old-fashioned method of wax seals. This process typically forces the metal into a rounded shape anyway and means less work to finish the coin. As coins had to exist in relatively large quantities, keeping them a round shape was best for all concerned.

When round coins are cut out, there is some metal left over every time. In a modern-day setting, one might argue that cutting coins into squares from a metal sheet would be more efficient. However, it’s not too much extra work to take the leftover metal and melt it down to use in the next batch.

Finally, a key modern reason for rounded coins is that round coins are convenient for transport within vending machines, etc, since they will roll easily. The same goes for arcade video games and any other machine that requires payment through coins.

No matter what their shape might be, coins have played an important role in the history of many countries. Here are a few books that can further satisfy our interest in how coins have shaped human history:

Where to Buy
Roman History from Coins: Some Uses of the Imperial Coinage to the Historian by Michael Grant
Money of the World
Ancient History from Coins


Roman History from Coins: Some Uses of the Imperial Coinage to the Historian by Michael Grant

Many countries now use paper money more than coins, but it’s worth learning what the coins say about certain cultures. In this work, the author looks at how the Romans used their currency for directing or even deceiving public opinion as well as the repercussions of this practice.

There’s a very interesting narrative here on how the imagery of coins related to the emperors’ propaganda back then. Those who have an interest in coins, as well as Roman history, will probably find this an enjoyable read.  

Money of the World: Coins That Made History by Ira and Larry Goldberg

This book illustrates the Millenia collection and tells us how Western civilization has transformed through the imagery of coins. It talks about the criteria of each coin that led it to become part of this collection.

With the colored pictures and the quality production, this work will be of great interties to coin collectors and students of art history. The photographs are beautiful and show enlargements of the coins for better viewing. While not every coin is included, the selection was done based on the largest circulations in their time period.

Ancient History from Coins (Approaching the Ancient World) by Christopher Howgego

This is another work that uses coins as a way to gain information about history. More specifically, it deals with what coins can tell us about the ancient world. Historians might not like to use coins as a form of evidence, but this analysis gives us many examples of how they can reflect major historical themes.

Overall, this is a useful book for supplementing the information we already have from other historical sources. It will be a good read for those who are interested in coins and what they have to tell us. Reviews also state that the writing is succinct and informative, making it a smooth-flowing read as well.