The widest central stripe on Thailand’s national flag is blue.
Thailand’s flag, called the Trairanga or “Tricolour,” has five horizontal stripes arranged red, white, blue, white, and red. The middle blue stripe is twice as wide as each of the four outer stripes, making it the flag’s dominant band. In the standard construction, the flag’s width is divided into six parts: the central stripe takes two parts and every other stripe takes one.
The present design was adopted in 1917 during the reign of King Vajiravudh, Rama VI. The blue was reportedly associated with the king’s birth day, Saturday, and is also commonly linked to solidarity with Thailand’s World War I allies. The flag’s nickname can mislead readers because it has five stripes, not three; “tricolour” refers to its three colors.
Thailand’s flag should not be confused with older Siamese flags that featured an elephant or different stripe arrangements. The key visual clue is the unusually broad dark-blue center.