// Workers AI · dad joke modeWhat did one "One-at coin" say? Coin-cidence?

1 at

Thailand
Value	1/64 Thai baht
Mass	(1860-1874) 7.20 g (1874-1888) 5.55 g (1888-1905) 5.80 g
Diameter	(1860-1874) 29 mm (1874-1888) 20 mm (1888-1905) 24 mm
Edge	Reeded
Composition	(1860-1874) tin-copper alloy (1874-1905) copper
Years of minting	1860-1905
Obverse
Design date	1888
Reverse
Design date	1888

The at coin (also spelled att; Thai: อัฐ) or the half-pai coin (Thai: กึ่งไพ) was a low-denomination coin used in the traditional pre-decimal currency system of Siam (modern-day Thailand). The at represented the unit known as the att or at, valued at 1⁄8 of a fuang or 1⁄64 of a baht. At coins were commonly issued during the Rattanakosin period and circulated widely as part of everyday small transactions. Early coins were cast in the characteristic pod-shaped "bullet money" (podduang) style, while later issues were struck as flat round coins as Siam modernized its currency system. The at, along with other non-decimal subunits, was discontinued when Thailand adopted the decimal baht–satang system in the early 20th century.

• Evolution of at
• 
  1862
• 
  1876
• 
  1888

Etymology

The term att is derived from the Sanskrit word aṣṭa (via Pali aṭṭha), meaning "eight." This nomenclature corresponds exactly to its mathematical position inside the historical currency matrix, where eight att pieces were legally required to equal one silver fueang (เฟื้อง).

Positioned directly above the solot,the absolute base tier of the economy, the att maintained a fixed value equivalent to exactly 1/64 of a standard silver baht (historically referred to in English diplomatic and trade accounts as the tical).

History

Early Substitutes

Before industrialized minting, transactions corresponding to the value of an att were largely settled using imported cowrie shells (bia), with roughly 100 to 200 shells equalling one att depending on market supply. For fixed metal denominations, the state relied on hand-poured clay, lead, or pewter tokens known as prak or phi, often issued by local gambling houses (rong huai) to facilitate micro-commerce.

Transition to Machine-Struck Coinage

Following the signature of the Bowring Treaty in 1855, the rapid commercialization of Bangkok's port necessitated a massive, standardized volume of low-denomination physical currency. The traditional hand-stamped manufacturing of bullet money (pod duang) proved structurally incapable of keeping pace.

1. The Tin-Pewter Era (Rama IV): Around 1862, King Mongkut (Rama IV) established the first mechanical minting facility within the Grand Palace. The early flat att pieces were struck from a locally sourced tin and lead alloy. These pieces featured the Royal Crown on the obverse and an elephant within a multi-pointed star wheel (Chakra) on the reverse. However, the soft alloy degraded rapidly under circulation wear and tropical conditions.
2. The Copper Era (Rama V): To remedy the durability problems of tin coinage, King Chulalongkorn (Rama V) modernized production by securing contracts with European institutions. The state transitioned to durable copper blanks outsourced to the Heaton Mint in Great Britain and later the Hamburg Mint in Germany.

Design

Numismatists isolate two primary definitive series for the machine-struck copper att coins issued during the reign of King Chulalongkorn:

The Chulalongkorn Monogram Series (1874–1883)

Struck primarily in Birmingham, this series prioritized royal heraldry over portraiture to conform with traditional Siamese taboos against depicting the monarch's likeness on common items:

• Obverse: Features the stylized Royal Cipher of King Rama V, containing the interlocking Thai characters จปร (Chulalongkorn Paramin R), surmounted by the Great Crown of Victory (Phra Maha Phichai Mongkut).
• Reverse: Features the explicit textual value inscription อัฐ ๘ อันเฟื้อง (Att, 8 pieces [equal] a Fueang). The text is elegantly framed by a woven botanical wreath composed of Cassia javanica (Java cassia) foliage and ears of rice.
• Dating: Coins from this minting period bear traditional numbers from the Chula Sakarat (CS) civil calendar, with the most common issues stamped with the years ๑๒๓๖ (CS 1236 / 1874 CE) and ๑๒๔๔ (CS 1244 / 1882 CE).

The Phra Siam Devadhiraj Series (1887–1905)

Following legal reforms and closer diplomatic alignments with Western empires, the coinage design was radically altered to adopt European monarchical conventions:

• Obverse: Displays a left-facing portrait bust of a young King Chulalongkorn dressed in Western-style military attire, bordered by the royal title inscription.
• Reverse: Features Phra Siam Devadhiraj—the anthropomorphic guardian deity and national personification of Siam—seated on a stylized throne holding a trident. The deity leans on a shield containing the tripartite Siamese Royal Coat of Arms, which visually represented Siam proper (the three-headed Erawan elephant), Lan Xang/Laos (the white elephant), and the Malay vassal states (crossed krises).
• Dating: This series discarded the Chula Sakarat system in favor of the Rattanakosin Era (RS) calendar, which calculated years from the founding of Bangkok in 1782. Notable att mintages bear dates such as ร.ศ. ๑๑๕ (RS 115 / 1896 CE) and ร.ศ. ๑๒๒ (RS 122 / 1903 CE).

Demonetization

The complex mathematical nature of the non-decimal base system became an administrative bottleneck as Siam sought to modernize its national treasury, customs duties, and international trade accounting. In 1897, King Chulalongkorn introduced a decimalized system, standardizing the national currency into a clean structure where 1 Baht equaled 100 Satang.

The att, along with the solot and other legacy fractional pieces, was officially stripped of its legal tender status on May 17, 1909.

See also

• Thai baht
• Solot coin
• Siao coin
• Sik coin
• Fuang coin