Asian Date Converter for Banknotes and Coins

Dates on Asian paper money and coins are not always expressed in the Gregorian calendar. A Thai coin may carry a Buddhist Era year, a Japanese coin may be dated by an emperor’s reign, a Taiwanese issue may use the Republic of China calendar, and an Islamic coin may use a lunar Hijri date. Even when the calendar is known, the printed numerals may be unfamiliar.

This Asian date converter is designed for numismatic year identification. Enter the year exactly as it appears, including supported Asian numerals, select the relevant dating system and convert it into a Common Era year or range. You can also reverse the conversion by entering a CE year. Because several Asian calendars begin during a Gregorian year rather than on 1 January, some results correctly show two possible or overlapping CE years.

For collectors, the reference works as both a banknote date converter and a coin date converter. It also serves as an Asian calendar converter for the supported regional systems and as a Buddhist year converter for dates expressed in the Buddhist Era.

The Asian Date Converter above is intentionally limited to systems that can produce a useful result from one printed year. The following important systems are not offered in its date-system menu because a second identifier, a historical table or contextual evidence is essential. They remain highly relevant when dating Asian banknotes and coins.

Japanese nengō or imperial era names

A Japanese date combines an era name with an era year. For modern numismatic material, the principal eras are Meiji (1868), Taishō (1912), Shōwa (1926), Heisei (1989) and Reiwa (2019). To obtain the CE year, add the era year minus one to the era’s starting CE year. For example, Shōwa 12 is 1926 + 11 = 1937 CE. The first year may be written 元年, meaning year 1. A transition year can belong to two eras, so the month and day may be necessary.

Chinese imperial nianhao or reign titles

Imperial Chinese dates pair a reign title with a numbered year. The basic method is the same: identify the reign title, find its first CE year, then add the reign year minus one. For example, Guangxu began in 1875, so Guangxu year 20 corresponds broadly to 1894. Exact attribution still requires attention to the lunar new year, accession practices, mint, inscription and whether a coin continued to be made with an older legend. China used many reign titles across numerous dynasties, so a year number without its title cannot be converted responsibly.

Vietnamese reign-title dates

Many Vietnamese coins use an imperial era title rather than a continuously numbered national calendar. First identify the ruler and era name from the characters, then calculate from that era’s first year in the same way as a Chinese nianhao. Some titles resemble Chinese inscriptions, and imitation, private, presentation and later-cast pieces complicate attribution. A specialist Vietnamese cash-coin reference is safer than treating the visible characters as a simple arithmetic date.

Ganzhi stem-branch cycle

The Chinese sexagenary cycle combines one of ten heavenly stems with one of twelve earthly branches to produce 60 names. A designation such as Jiazi (甲子) repeats every 60 years and therefore cannot identify one CE year by itself. Use a known ruler, reign title, issue type or narrow historical period as the anchor, then test candidate years at 60-year intervals. The cycle is also encountered in Japan, Korea and Vietnam under local readings.

Korean imperial era names

Late Korean imperial dates may use Gwangmu (光武), beginning in 1897, or Yunghui (隆熙), beginning in 1907. Add the era year minus one to the starting year: Gwangmu 5 is 1897 + 4 = 1901 CE, while Yunghui 3 is 1907 + 2 = 1909 CE. Because the eras overlap their transition year in calendar terms, a full date may require closer checking.

Tibetan Rabjung cycles

A Tibetan year may be identified by a numbered 60-year Rabjung cycle and a year within that cycle. Both values are needed. For the commonly used numbering beginning with cycle 1, year 1 in 1027 CE, the reference formula is CE = (cycle − 1) × 60 + cycle year + 1026. Thus cycle 16, year 25 gives 1951 CE. Some coins use animal-element year names instead, which repeat and must be anchored by the type and historical context.

Regnal, accession and local lunisolar dates

Some Asian issues count from a ruler’s accession, a revolution, an independence declaration or another local epoch. Others use regional forms of the Saka, Vikram, Buddhist, Islamic or lunisolar calendars whose year boundaries differ from the simplified rules used by a year-only calculator. Ottoman and Turkish material may also require distinguishing lunar Hijri, fiscal Rumi and Gregorian dates. In these cases, identify the issuer and inscription first, consult an authority-specific catalogue, and use a full day-month-year converter when the complete date is present.

No practical web page can list every reign title and local calendar used across all periods of Asian history. The systems above cover the principal additional methods likely to be encountered by collectors, while the calculator focuses on the formulas that remain useful when only a year is known.

A Nepalese Bikram Sambat, Saka, Solar Hijri, Nepal Sambat or Kollam year overlaps portions of two Gregorian years. Without the printed month and day, returning only one CE year would imply more precision than the inscription provides. The same principle applies to a lunar Hijri year, whose beginning can also vary by a day between calculated and observation-based calendars.

Ganzhi stem-branch names repeat every 60 years, while Chinese nianhao, Japanese nengō and Korean imperial dates require the correct era title. These systems are explained in the manual reference rather than placed in the one-field calculator. Dates on coins may additionally combine an accession year with a regnal year, use a frozen date after the original year, or reproduce an earlier date on a restrike.

The date printed on an object is not necessarily its exact production or circulation date. It may refer to a decree, authorization, calendar year, accession year, commemorative event, series or reused design. Always compare the result with a recognized catalogue and the history of the issuing authority.

For further verification of complete dates, collectors may consult the Okinawa Institute of Science and Technology Japanese year converter, the Hong Kong Observatory Gregorian–Lunar conversion tables, and the U.S. Naval Observatory’s Islamic calendar reference. These resources provide useful calendar context but do not authenticate or attribute a banknote or coin.