Although the vast majority of coins are circular due to their origin as flattened pieces of metal forged between tongs, coins are made in a variety of other shapes, including squares, diamonds, hexagons, heptagons, octagons, decagons, and dodecagons. They have also been struck with scalloped (wavy) edges, and with holes in the middle. Coins in the shape of polygons often have rounded edges or are Reuleaux polygons.
This article focuses mainly on circulating coins; a number of non-circulating commemorative coins have been made in special shapes, including guitars, pyramids, and maps. There is a list with more unusual shapes of non-circulating commemorative coins at the end of this page that all have been issued officially by various countries.
Triangular The Cook Islands have a circulating 2 dollar triangular coin with rounded corners.2 Dollars – Elizabeth II (3rd portrait) – Cook Islands. Numista.
A triangular coin with a face value of £5 was commissioned by the Isle of Man to commemorate the 2007–2008 Tutankhamun exhibition at The O2 Arena in London. It became legal tender on 6 December 2007, but it was rarely used because each coin cost £15 to purchase from the Isle of Man Post Office.Cleland, Gary. "Pyramid coin a nightmare for pockets", The Daily Telegraph, December 6, 2007, page 13.
Other triangular coins issued earlier include: Cabinda coin, Bermuda coin, Uganda Millennium Coin and Polish Sterling-Silver 10-Zloty Coin.
Squares and diamonds
Indo-Greek coins were often square. Aruba has a large circulating square 50 cents coin.50 Cents – Beatrix / Willem-Alexander (magnetic) – Aruba. Numista.
Many countries have struck square coins with rounded corners. Some of these, such as the Netherlands zinc 5 cent coin of World War II (1941–1943)5 Cents – Wilhelmina I (German Occupation) – Netherlands – Numista. En.numista.com. Retrieved on 2021-05-23. and the Bangladesh 5 poisha coin (1977–1994)5 Poisha (FAO) – Bangladesh. Numista. are oriented as a square, while others, such as the Netherlands 5 cents (1913–1940),5 Cents – Wilhelmina – Netherlands – Numista. En.numista.com. Retrieved on 2021-05-23. the Netherlands Antilles 50 cent, the Bangladesh 5 poisha (1973–1974)5 Poisha – Bangladesh. Numista. and the 1981 Jersey 1 pound coin,1 Pound – Elizabeth II (Battle of Jersey) – Jersey. Numista. are oriented as a diamond. Ceylon (the current Sri Lanka) issued its first square coin in 1909, followed by several others.5 Cents – Edward VII – Ceylon. Numista. India has had various circulating square coins as well, like denominated and 2 anna coins, Anna – George VI – India – British. Numista. as well as 1 and 5 paisa coins.1 Paisa – India. Numista.
Siege money, such as klippe coins or the siege money of Newark, was often in the shape of a lozenge (rhombus).
Pentagonal The Mutawakkilite Kingdom of Yemen introduced pentagonal and rial coins in 1948. Riyal – Ahmad – Mutawakkilite Kingdom. Numista. Riyal – al-Nasir Ahmad bin Yahya – Mutawakkilite Kingdom. Numista. In 2014 Transnistria was the next country to issue a circulating pentagonal 5 rubles hard plastic coin.5 Rubles – Transnistria. Numista.
Hexagonal The Belgian Congo had a hexagonal 2 franc coin,2 Francs – Léopold III – Belgian Congo. Numista. as did the Kingdom of Egypt (2 piastres, also known as 2 qirsh).2 Qirsh – Farouk – Egypt. Numista. India used to have 3 paise and 20 paise coins that were hexagonal with rounded corners.3 Paise – India. Numista.20 Paise – India – Numista. En.numista.com. Retrieved on 2021-05-23. The Burmese 25 pyas is scalloped hexagonal.25 Pyas – Myanmar. Numista.
Heptagonal The Madagascar 10 ariary coin is seven-sided.10 Ariary (motto A) – Madagascar. Numista. The British twenty pence and fifty pence coins are heptagonal Reuleaux polygons,20 Pence – Elizabeth II (2nd portrait) – United Kingdom – Numista. En.numista.com. Retrieved on 2021-05-23.50 New Pence – Elizabeth II (2nd portrait) – United Kingdom – Numista. En.numista.com. Retrieved on 2021-05-23. as is the United Arab Emirates 50 fils coin, the Barbados one dollar coin,1 Dollar – (large type) – Barbados. Numista. and several coins from Botswana.5 Thebe – Botswana. Numista. Many countries in the Commonwealth of Nations have issued heptagonal coins. Reuleaux polygons have constant width, which means the currency detectors in coin-operated machines do not need an extra mechanism to detect shape.
Octagonal
The Chile 1 peso and 5 pesos coins issued from 1992 to 2015 are eight-sided.1 Peso – Chile. Numista.5 Pesos – Chile. Numista. So was the old circulating Malta 25 cent coin commemorating Malta's first anniversary of the republic25 Cents (1st Anniversary of Republic) – Malta – Numista. En.numista.com. Retrieved on 2021-05-23. and some California gold coins. Some other countries that have issued circulating octagonal coins are Lebanon50 Līrah / Pounds (stainless steel) – Lebanon. Numista. and Sierra Leone.50 Leones – Sierra Leone. Numista.
Nonagonal In 1972 the first country to issue a circulating nine-sided coin was Thailand with a 1972 regular 5 baht coin,5 Baht – Rama IX – Thailand. Numista. followed by Kenya in 1973 with a special issue coin. The third and final circulating nonagonal coin issued in the 20th century and is the regular 1976 50 cent coin from Tuvalu.1 Dollar – Elizabeth II (2nd portrait) – Tuvalu. Numista. Currently, the Philippines issues nonagonal 5-peso coins from 2019 as an enhanced design of the round version to make it distinct from the other denominations.
Decagonal Hong Kong issued a ten-sided 5 dollar coin from 1976 to 1979,5 Dollars – Elizabeth II (2nd portrait) – Hong Kong. Numista. while the Philippines issued ten-sided two piso (peso) coins from September 30, 1983 to March 9, 1991.2 Piso – Philippines. Numista. Some other countries that have issued ten-sided circulation coins are Chile,50 Pesos – Chile. Numista. the Dominican Republic,1 Peso (Montesinos, Enriquillo, Lemba) – Dominican Republic. Numista. Jamaica50 Cents (Wide legend) – Jamaica. Numista. and Madagascar.20 Ariary (motto A) – Madagascar. Numista.
Hendecagonal The old Indian 2-rupee coin was eleven-sided,2 Rupees (National Integration; hendecagonal type) – India. Numista. while the Canadian one dollar coin is an eleven-sided Reuleaux polygon.1 Dollar – Elizabeth II (2nd portrait) – Canada – Numista. En.numista.com. Retrieved on 2021-05-23. Also Madagascar has issued some circulating eleven-sided coins.50 Ariary (motto A) – Madagascar. Numista.
Dodecagonal
Many countries have struck twelve-sided coins, mostly countries belonging to the Commonwealth of Nations. Several of these are threepence coins from the pre-decimal pound.3 Pence – George VI – Fiji. Numista. Shilling – Elizabeth II (1st portrait) – Jersey – Numista. En.numista.com. Retrieved on 2021-05-23. Coins currently circulating include the British one pound coin,1 Pound – Elizabeth II (5th portrait; Nations of the Crown) – United Kingdom – Numista. En.numista.com. Retrieved on 2021-05-23. 50 cent coins from Australia,50 Cents – Elizabeth II (2nd Portrait – Dodecagonal type) – Australia. Numista. Fiji50 Cents – Elizabeth II (2nd portrait) – Fiji. Numista. and the Solomon Islands,50 Cents – Elizabeth II (3rd portrait; non-magnetic) – Solomon Islands. Numista. the Tongan 50 seniti coin50 Seniti – Taufa'ahau Tupou IV – Tonga. Numista. and the circulating commemorative Croatian 25 kuna coins.25 Kuna (Danube Region) – Croatia – Numista. En.numista.com. Retrieved on 2021-05-23.
Tridecagonal
In 1993, the Czech Republic was the first country to issue a 13 sided 20 koruna coin.20 Korun – Czech Republic. Numista. In 2013, Tunisia followed with a 13-sided 200 millièmes coin.200 Millièmes – Tunisia – Numista. En.numista.com. Retrieved on 2021-05-23.
Pentadecagonal A 5 dirham commemorative coin from the UAE in 1981 had 15 sides, commemorating the 15th century of Hejira.5 Dirhams – Zayed (15th Hijrah Century) – United Arab Emirates – Numista. En.numista.com. Retrieved on 2021-05-23.
Scalloped
Many countries have coins with scalloped (wavy) edges. These usually have twelve bumps (e.g. the Vanuatu 100 vatu or the Hong Kong 20 cents), but can have other numbers such as eight (the Eswatini 10 cents or the Ang Bagong Lipunan Philippine five centavo coin) or sixteen (the Libya 50 dirhams).
Holed
Often a round coin will have a central hole. In some countries this was to allow them to be strung together, while other reasons include difficulty of counterfeiting and ability for visually impaired people to distinguish them from other coins.
Some coins give the impression that holes were used to save metal, though it may not be possible to prove with certainty that this was the reason for creating the holes. An example of such a coin with a fairly large hexagonal hole is a undated tin 1 cash coin, minted in the period 1550–1596, that circulated in the Banten Sultanate on Java and Sumatra (Indonesia).1 Cash – Malay peninsula. Numista. Also, several tin 1 pitis coins with exceptionally large round holes, of which some were made in octagonal coins, were used in Jambi Sultanate on Northern Sumatra (Indonesia).1 Pitis – Malay peninsula. Numista. Due to the soft metal tin used to make these thin old coins, they can easily be bent. In the years 1943–1947 India produced 1 pice coins for circulation with very large holes,1 Pice – George VI – India – British. Numista. continued by Pakistan producing 1 pice coins of equal shape in the years 1948–1952.1 Pice – Pakistan. Numista.
Chinese cash coins had a square hole, while many modern coins have a round hole. Examples include the Japan 5 yen coin and 50 yen coin, and the Danish 1, 2 and 5 krone coins.
Other shapes Rectangles: In the Edo period Japan issued several circulating silver and gold rectangular coins,1 Shu "Kaei Isshugin" – Japan. Numista.2 Shu – Tempo (Edo mint) – Japan. Numista. as well as a copper clad lead issue with a hole.100 Mon "Dōzanshihō Tōhyaku" – Kubota Domain. Numista.
Near oval: Japan also issued various near oval coins in the Edo period.Chōgin "Genbun Chōgin" (6 stamps) – Japan. Numista.100 Mon "Tenpōtsūhō" – Japan. Numista.1 Ryō "Man'en Koban" – Japan. Numista.
Half circle: for Barbados Spanish coins were cut in half, it is hard to detect originals though, many forgeries exist.1 Bit – Barbados. Numista.
Additional shapes among non-circulating coins
Triangular: Bermuda has some special issue triangular coins from 1997 onward with curved edges.1 Dollar – Elizabeth II (Wreck of the Sea Venture) – Bermuda. Numista. The Isle of Man has some triangular special issue coins where the triangle is not regular (the angles are not all 60 degrees).1 Crown – Elizabeth II Tutankhamun: Death Mask. Numista.
Octagonal: The U.S. Panama–Pacific commemorative 50 dollar coins of 1915 is shaped like a true octagon.50 Dollars (Panama–Pacific Exposition) – United States. Numista.
Tetradecagonal: In 1976, Malaysia was the first country to issue 14-sided coins, the non-circulating 10 (silver) and 200 (gold) ringgit.10 Ringgit – (3rd Malaysian Plan) – Malaysia. Numista. Australia started to issue a series of non-circulating 14-sided 50 cents coins dedicated to the Chinese zodiac in 2012.50 Cents – Elizabeth II (4th Portrait – Year of the Dragon) – Australia. Numista.
Rectangular: Jersey50 Pence – Elizabeth II (The Battle of Hastings 50 Pence Silver Coin-Bar) – Jersey. Numista. and Fiji1 Dollar (Berlin) – Fiji. Numista. have issued non-circulating rectangular coins.
Oval: Fiji and Poland have issued some non-circulating oval coins.10 Dollars – Elizabeth II (Apocalypse I Prophecy of Maya Calendar) – Fiji. Numista.10 Złotych (Grunwald) – Poland. Numista.
Quarter circle: Poland has issued a 10 złotych coin in the shape of a quarter circle.10 Złotych (Expo 2005) – Poland – Numista. En.numista.com. Retrieved on 2021-05-23.