Coins in Common Circulation
Coins circulated during this present reign have been produced and issued since 1950. At first, there were only four denominations, namely 50 satang, 25 satang, 10 satang, and 5 satang. In 1957, 1 bath cupro nickel coin with 3% of silver content bearing the state Coat-of-Arms was issued for the first time. In 1972, the government discontinued the 5-baht banknote. Consequently, the 5-baht coin was issued for the first time. The first type of 5-baht coin was nine-sided and made of copper and nickel. As a result, there were six denominations of coins in circulation used between 1972 and 1987, namely 5 baht, 1 baht, 50 satang, 25 satang, 10 satang, and 5 satang.
Coins in circulation have been constantly adjusted in terms of design, type of metal used, specification, and size. These adjustments, however, have sometimes been carried out on certain denominations only. Until 1987, the Treasury Department issued a new set of coins in all denominations, and issued a 10-baht coin to be used instead of the 10-baht banknote that was discontinued by the Bank of Thailand, as well as issuing a 1-satang coin in order to increase the decimal nature of the system. The reverse of this new set of coins bore the pattern of important regional religious sites revered by Thais. This new set of coins in common circulation consisted coins of eight denominations, namely 10 baht, 5 baht, 1 baht, 50 satang, 25 satang, 10 satang, 5 satang, and 1 satang.
There was a significant change in the system for coins in circulation in 2005 when the Treasury Department issued a 2-baht coin, adopting the binary decimal system for the first time. The issue of a 2-baht coin between the 1-baht and 5-bahts coin was intended to decrease the demand for the 1-baht coin. This 2-baht coin is made of nickel-plated steel and the mill on its edge has been adjusted so that visually impaired people can easily distinguish it from other coins in circulation.
After adding the 2-baht coin to the system, there were nine denominations of coins in circulation, namely 10 baht, 5 baht, 2 baht, 1 baht, 50 satang, 25 satang, 10 satang, 5 satang, and 1 satang. However, because the price of the metal employed for the manufacture of these coins had increased greatly, the production cost for many denoninations of coin was higher than their face value. As a result of this, in 2008, the Treasury Department issued a new set of coins in circulation; the obverse design of every denomination of coin was changed. The royal portrait of His Majesty the King, employed since 1987, was replaced by a royal portrait of His Majesty the King at present, and the types and weight of metal were adjusted to lower the production cost. The nickel-plated steel of the 2-baht coins was replaced by an aluminum bronze alloy in order to distinguish the 2-baht coin from the 1-baht coin in terms of colour.
The 10-baht Coin
The new 10-baht coin is still a bi-color coin, with a cupro nickel (white) outer ring made of copper and nickel and a yellow inner disc made of aluminum bronze. It was designed to be compatible with pre-existing vending machines and has the qualification that is difficult to counterfeit, unlike the previous model. The only adjustment to the design was on the obverse side; the royal portrait of His Majesty the King, employed since 1987, was replaced by a royal portrait of His Majesty the King at present. The pattern on the reverse is still the same, depicting Phra Prang of Wat Arun Ratchawararam, Bangkok.
The 5-baht Coin
As the market price of metal used for coin production had constantly increased since 2006, the face value of many denominations of coin was lower than the cost of metal used in production. This was especially true for the 5-baht coin, the production cost of which was higher than its face value, causing a high risk of counterfeiting both for its use in the marketplace and for vending machines. As a result, the Treasury Department decided to decrease the weight of the 5-baht coin. It is still made of cupro-nickel-clad copper like the old model but the weight has been reduced from 7.5 grams to 6 grams. It"s thickness, however, is still compatible with the manufacturing process and suitable for usage today. The only adjustment to the design was on the obverse side; the royal portrait of His Majesty the King, employed since 1987, was replaced by a royal portrait of His Majesty the King at present. The design on the reverse is still the same, depicting the ordination hall of Wat Benchamabophit, Bangkok.
The 2-baht Coin
The Treasury Department has tried to find a solution to the related problems of production cost and confusion in the use of the 1-baht coin and the original model of the 2-baht coin; it found that a change in the type of metal employed for the manufacture of each denomination of coin would help reduce the production cost and effectively distinguish one type of coin from the other. As a result, the metal used for the new model of the 2-baht coin was changed to an aluminum-bronze alloy. Although this has a higher production cost than the old nickel-plated steel, it is effective for distinguishing this kind of coin from other coins in circulation. Moreover, because of the use of a metal of a different colour, there is no need to recall the old model. The weight of the coins has also been reduced from 4.4 grams to 4 grams.
The only adjustment to the design was on the obverse side; the royal portrait of His Majesty the King, employed since 1987, was replaced by a royal portrait of His Majesty the King at present. The design on the reverse is still the same, depicting the Golden Mount of Wat Saket, Bangkok.
The 1-baht Coin
In order to reduce production cost, the metal used for the production of the new 1-baht coin has been changed to nickel-plated steel, which is inexpensive, while the size and the thickness remain the same. It is still compatible with vending machines. Moreover, the weight has been reduced from 3.4 grams to 3 grams. The only adjustment to the design was on the obverse side; the royal portrait of His Majesty the King, employed since 1987, was replaced by a royal portrait of His Majesty the King at present. The design on the reverse is still the same, depicting the Phra Sri Rattana Chedi of the Temple of the Emerald Buddha (Wat Phra Kaeo), in the Grand Palace, Bangkok.
The 50-satang Coin
The metal used for the new model of the 50-satang coin has been changed to copper-plated steel, which is widely used abroad for coins of low denomination such as 1-cent coins in the countries using the euro and 1-penny coins in the United States. The weight of the 50-satang coin is approximately 2.4 grams. The only adjustment to the design was on the obverse side; the royal portrait of His Majesty the King, employed since 1987, was replaced by a royal portrait of His Majesty the King at present. The design on the reverse is still the same, depicting the Chedi Wat Phra That Doi Suthep, Chiang Mai.
The 25-satang Coin
The metal used for the new model of the 25 satang coin has been changed to copper-plated steel, with the same weight as the earlier coin, approximately 1.9 grams. The only adjustment to the design was on the obverse side; the royal portrait of His Majesty the King, employed since 1987, was replaced by a royal portrait of His Majesty the King at present. The design on the reverse is still the same, depicting the Phra Boromathat Chedi Nakhon Si Thammarat, Nakhon Si Thammarat.
The 10-satang Coin
The metal used for the new model of the 10-satang coin has been changed to pure aluminum. This change of metal does not affect the production cost of the coin. The Treasury Department itself manufactures the 10-satang, 5-satang, and 1-satang because the demand for these coins is quite low compared with coins of other denominations. The weight of the new coin remains the same, approximately 0.8 grams. The only adjustment to the design was on the obverse side; the royal portrait of His Majesty the King, employed since 1987, was replaced by a royal portrait of His Majesty the King at present. The design on the reverse is still the same, depicting the Chedi Phra That Choeng Chum, Sakon Nakhon.
The 5-satang Coin
The metal used for the new model of the 5-satang coin has been changed to pure aluminum. Moreover, the diameter has been adjusted from 16 millimeters, which is equal to that of the 25 satang coin, to 16.5 millimeters. The weight of the coin remains the same, approximately 0.6 grams. The only adjustment to the design was on the obverse side; the royal portrait of His Majesty the King, employed since 1987, was replaced by a royal portrait of His Majesty the King at present. The design on the reverse is still the same, depicting the Phra Pathom Chedi, Nakhon Pathom.
The 1-satang Coin
The metal used for the new model of the 1-satang coin has been changed to pure aluminum. The weight of the coin remains the same, approximately 0.5 grams. The only adjustment to the design was on the obverse side; the royal portrait of His Majesty the King, employed since 1987, was replaced by a royal portrait of His Majesty the King at present. The design on the reverse is still the same, depicting the Chedi Wat Phra That Hariphunchai, Lamphun.