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Do you know how to identify dates on coins? Part 3

By rcintas on the

This week we finish the series of posts that will help you out to identify the date of different coins. You can find the first part in here: Do you know how to identify dates on coins? Part 1 and the second one in here: Do you know how to identify dates on coins? Part 2.

Arab Coin


The date on the modern coins of Japan, is based in the reign period of each of its emperors. This way the first year of reign is the year one, the second is year two, and so on, until a new emperor comes and the count is reseted.

So for dating the coins, it is essential to identify first to which emperor they belong. The emperors are:

Mutsuhito (Meiji) 1.868 - 1.912 1 - 45 明治天皇
Yoshihito (Taisho) 1.912 - 1.926 1 - 15 大正天皇
Hiroito (Showa) 1.926 - 1.989 1 - 64 昭和天皇
Akihito (Heisei) 1989 - 1 - 平成天皇

In order to calculate the correspondence with the Gregorian calendar we need to sum the year and the start of the reign of the emperor with the value that is written in the coin.

When writing the date in the coins there are also some rules to take into account:

    • There is only one number: correspondent to the year. However one exception exists, for the first year of reign the first character is used ( Japanese Character ) instead of the character one (一).

明治 A 年

    • There are two numbers and the second, (the one situated near the date symbol) is a 10, then we have to multiply them.

明治 A [十,百 ] 年
date ⇒ A * [10,100]

    • There are two numbers and the first one (the one situated near the emperor symbols), is a 10 then we have to sum them up.

明治 [十,百 ] A 年
date ⇒ A + [10,100]

    • There are three numbers, in this case the second one will always be a 10, so what it has to be done is first multiply this second by the first one and sum the result to the third one

明治 C [十,百 ] A 年
date ⇒ C * [10,100] + A

Practical example:

Japanese coin

So, for a coin with the inscription:

昭和 ⇒ Showa Emperor
六十三 ⇒ 63
63 + 1926 = 1989


Coins from Thailand can be dated following three different eras:

  • The “Small” era CS ⇒ [638BC - 1782AC]
  • The “Bangkok” era RS ⇒ [1782AC - 1913AC]
  • The “Buddhist” era BE ⇒ [1913AC - ]

The “Small” era CS
It is the Chula-Sarakat (CS) calendar and it starts in the year 638 B.C.

In order to calculate the dates in the gregorian calendar you need to aggregate 638 years to the date on this coin.

๑๒ ๓๘ ⇒ 1238
1238 + 638 ⇒ 1876

If in the coin the number that we see is 1238, then in the gregorian calendar (ours) the date would be: 1238+638=1876. So the coin would indicate the year 1876 in our calendar.

The “Bangkok” RS era
This calendar is also called Ratanakosind-sok (RS). This era starts in the year 1782 with the foundation of the new capital in Bangkok.

In order to convert a date in this calendar to ours you only need to sum up the date of the coin to the starting year of the era, 1781.

๑๒๗ ⇒ 127>
127 + 1781 ⇒ 1908

The “Buddhist” BE era
Since 1913 the coins from Thailand use the Buddhist calendar (BE = Buddhist Era). The starting year of the Buddhist calendar is 543 A. C. of the Gregorian calendar and it corresponds to the death of Bud. The years of this calendar are divided in 12 months between 28 and 31 days as in the Gregorian calendar.

In order to calculate the Gregorian year we need to subtract 543 to the date that appears on the coin:

๒๕๐๙ ⇒ 2509>
2509 - 543 ⇒ 1966

Practical example:

Thai coin Thai coin date

The coin belongs to the Buddhist era, therefore to the value of the date that appears in the coin you need to subtract 543 in order to obtain its correspondence with the gregorian calendar.

๒๕๐๙ ⇒ 2509
2509 - 543 ⇒ 1966

Here we finish the post series dedicated to identify the date on coins. Leave your comments below!