One-baht coin
The one-baht coin is a denomination coin of the Thai baht, the Thai currency unit.
Like all coins in Thailand, its obverse features the King of Thailand, Vajiralongkorn, and previously Bhumibol Adulyadej. The newest set of coins features King Vajiralongkorn's royal monogram on the reverse side while the coins of the previous set featured Wat Phra Sri Rattana Satsadaram or Wat Phra Kaew, the royal temple in Bangkok's Grand Palace complex.
It is commonly called rian baht by Thai speakers.
Series
2009 changes
On February 2, 2009, the Treasury Department announced changes to several circulating coins. The composition of the one-baht coin changed from cupronickel to nickel-clad iron, reducing the mass from 3.4 grams to 3.0 grams. The obverse image has also been updated to a more recent portrait of the king.2018 series
The Ministry of Finance announced on March 28, 2018 that the first coins featuring the portrait of His Majesty King Maha Vajiralongkorn Bodindradebayavarangkun will be put in circulation on April 6.History
1855-1869, Gift from queen Victoria
During the reign of King Rama IV, also known as Mongkut, Siam undertook significant monetary reforms. To familiarize the population with “flat” coins and to compensate for the limited supply of traditional bullet money, cowrie shells, South American reais, and various regional currencies then in circulation, the government introduced in 1856 a series of transitional silver and gold coins produced by manual striking.In 1857, Queen Victoria of the United Kingdom presented King Mongkut with a small hand-operated coining press. The coins struck using this device became known as Rien Bannakarn. Due to the low production capacity of the manual press, minting soon ceased. However, Siam continued its efforts to establish a modern mint and subsequently acquired a steam-powered coining press from England. To house the new equipment, King Mongkut ordered the construction of the Sitticarn Mint within the palace grounds. The first coins produced on the new press utilized the dies of the Royal Gift Coins. These issues circulated alongside traditional sweat duang bullet coins, whose minting had been discontinued. Bullet coins were gradually withdrawn, melted down, and reused as metal for later flat-coin issues. A small number of sweat duang pieces were later struck by the next monarch as commemorative issues in memory of deceased relatives.
Also in 1857, the government officially recognized exchange rates for certain foreign currencies that were already widely used in trade: 1 baht was set equal to 0.6 Straits dollars, and 5 baht to 7 Indian rupees.
The first machine-struck flat coins of Siam were released in 1860. This initial series comprised seven silver denominations: 1 sik, 1 fuang, 1 and 2 salung, and 1, 2, and 4 baht. Additional denominations followed, including tin 1 solot and 1 att coins in 1862, copper 2 and 4 att in 1865, and gold 2½, 4, and 8 baht coins in 1863. Many of these coins were struck at the Birmingham Mint and became popularly known as Rien. The word Rien is derived from real, a trading currency similar to the newly introduced coins.
A total of 2,400 one-baht Bannakarn coins were struck. They circulated concurrently with the later one-baht coins of 1860, which were produced in far greater numbers on the new steam-powered minting press ordered from England. Because the differences between the Bannakarn pieces and the 1860 one-baht coins were not widely recognized, both types remained in circulation together. When these issues were eventually withdrawn and melted, the Bannakarn coins were destroyed along with the rest, making surviving examples rare.
According to curator’s comments recorded in 1994, the “Royal Gift” coins were presented to the British Museum in 1857 by the Earl of Clarendon. The notes outline the historical context of minting reforms during the reign of King Mongkut, a period marked by the opening of Siam to international trade and the transition from traditional bullet-shaped currency to machine-struck flat coinage.
In 1856, enquiries were made in Britain about the cost of supplying modern minting equipment to Siam. Correspondence between King Mongkut and Sir Robert Schomburgk, the British Consul, indicates that by February 1859 there was an acute shortage of silver bullet money, prompting the King to seek a press capable of producing 100,000 ticals per day. In March 1858 Schomburgk was instructed to procure a minting machine costing £2,000, along with two engineers to operate it. By this time, however, Queen Victoria had already gifted a small coining press to the King—adequate for experimental purposes but insufficient for large-scale production.
Schomburgk subsequently discovered that Siamese envoys had independently ordered a complete minting system from the British firm Taylor of Birmingham, the same manufacturer that had produced the Queen’s gift press. Their order, costing £3,000, was fulfilled, and the machinery arrived in Bangkok in 1858–1859. It was installed within the Grand Palace, and the official edict announcing the issuance of the new flat silver ticals was dated 17 September 1860.
Throughout this era, Siam lacked a modern institutional framework to regulate its money supply. The Treasury operated primarily as a passive intermediary: When silver entered the country through trade, merchants sold it to the Treasury and received baht coins and when silver was required for the payment of imports, baht coins were exchanged back for silver bullion.
Thus, the money supply fluctuated according to trade flows rather than formal monetary policy. The absence of regulatory tools meant that Siam’s monetary system was highly sensitive to global market developments, especially those affecting silver prices.
1869-1876, Transition
The designed slightly changed on the obverse where the Rama IV's seal used to be there, the coin was updated to contain Rama V's seal.1876-1909, Phasing out podduangs
During this era, podduangs and flat-coins co-circulate. The finess during this era was being standardized to 0.900 or 0.925 depending on where the coin is being minted. Prior to this, the standard floated around 0.900 to 0.960. Under the silver standard, the value of the baht depended on the amount of silver it contained. Official specifications placed the baht at approximately 15.292 grams, of which about 90.625% was silver. As Siam’s trade expanded during the second half of the nineteenth century, the nation experienced a net inflow of silver because its exports consistently exceeded imports. This silver was sold to the Royal Treasury, which returned newly minted baht coins in exchange. The process led to a gradual but continuous increase in the domestic money supply.After 1870, global silver prices began to fall as silver depreciated relative to gold on world markets. For Siam, the decline raised the domestic cost of imports—many of which had to be paid for in gold-standard currencies such as sterling—while simultaneously encouraging exports. Concern over the rising cost of essential imports and the burden of servicing foreign loans denominated in sterling contributed to growing sentiment within the government to end reliance on the silver standard. In 1902, Siam formally abandoned silver convertibility, an important step toward a stabilized and modernized monetary system. Thus, abandoning the bi-metallic system. Podduang gradually became less circulated due to the massive production of flat-coins, and was formally phased out by 1900.
The designs also started including dates since 1901
1893-1910, Decimalization
The reign of King Chulalongkorn saw major transformations in Siam’s monetary and fiscal systems, culminating in the adoption of a decimal currency structure. On 21 August 1898, the Siamese government formally announced its intention to transition from the traditional multi-denominational system, formerly comprising thirteen interrelated units, to a simplified decimal system modeled on Western standards. The principal architect of this reform was Prince Jayanta Mongkol, a half-brother of the king and Minister of Finance from 1896 to 1906, later celebrated as the “father of Thai banking.” Under the new system, the baht —a silver coin of approximately 15.033 g with.900 fineness—was divided into 100 satang, the term satang being derived from Pali with the meaning “one-hundredth.” The reform also retained the salung as an intermediate unit, as it aligned naturally with the new decimal structure.The decimalization prompted the introduction of a new series of copper-nickel coins in denominations of 2½, 5, 10, and 20 satang, representing Siam’s first modern minor coinage. Although the government officially announced the full transition to the decimal system on 25 November 1902, elements of the earlier system persisted for several years: bronze coins based on the old att unit continued to be minted until 1905, and silver baht-based coins remained in production until 1910. Further changes were made in 1908, when Rama V introduced 1, 5, 10,25,and 50 satang coins.
During 1907–1908, Rama V also commissioned a special issue of 1 baht silver coins from the Paris Mint, engraved by the noted French medalist Henri-Auguste-Jules Patey. These coins, depicting the king in middle age with a distinctive moustache, earned the popular nickname “mustache baht”. Although intended for circulation, they were not released before the king’s death in 1910 and were instead distributed by his successor, King Vajiravudh, at Rama V’s cremation ceremony. Upon ascending the throne, Rama VI retained the existing designs for small denominations, which continued to bear the legend “Kingdom of Siam”, maintaining continuity with the final years of his father’s reign.
Throughout all of this, the old 1876 series 1 baht coin were continuously circulated.