What it does
Many coins, notes and medals from South Asia, the Middle East and East Asia carry a date in a calendar that is not ours. An Islamic coin says AH 1300, an Indian one says Samvat 1976, a Kerala one says Kollam 1100. This tool turns that number into the common era (CE) year, the one used in catalogues and price lists.
Most of these calendars begin part way through our year, so a coin year usually covers two of ours, shown like 1882/83. For Islamic years you also get the day the year begins. You can go the other way too: type our year and see what it is in each calendar. A small table shows the Arabic-Indic and Devanagari digits so you can read the date itself. When you have the year, look the coin up with collection catalogue, or convert its old money with old money.
How to use it
- Choose Date on the coin to our year, or the second button for the other way round.
- Pick the calendar written on the coin.
- Type the year in ordinary digits (use the digits table if the coin has local ones).
- Read the CE year or years, and the note about when that calendar’s year starts.
What each setting does
- Calendar on the coin: which calendar the number belongs to. Islamic Hijri (AH) is the one most often found on coins.
- Year on the coin: the number as written. Japanese years count from 1 in each emperor’s era.
- Our year to every calendar: shows the matching year in all the calendars, with two answers where the calendar’s new year falls inside ours.
Worked example
AH 1300 begins on about 12 November 1882 and ends in 1883, so it is 1882/83 CE. Vikram Samvat 1976 is 1919/20, and Kollam 1100 is 1924/25. Thai Buddhist Era 2500 is 1957, one year only, because the Thai year starts on 1 January.
FAQs
Why two years? The calendar’s new year does not line up with 1 January. Which of the two years a coin belongs to depends on the month it was struck, which most coins do not show.
Is the Islamic start date exact? It is a calculated date. The month starts when the moon is sighted in many places, so it can be a day or two different.
Why is a Samvat result sometimes off by one? Different regions start the year in different months, so the offset is 56 or 57. The tool gives both.
Can it read a Chinese or Mughal regnal year? No. It handles calendars with fixed year counts. For regnal years use a catalogue.
Where the numbers come from
- Islamic (Hijri) years: the arithmetic tabular calendar (30-year cycle, 10,631 days), with day 1 of AH 1 on 16 July 622 (Julian). Real calendars based on moon sighting can differ by a day or two.
- Other eras: the fixed year offsets of each calendar (for example Vikram Samvat minus 57 or 56, Saka plus 78, Kollam plus 824, Thai Buddhist Era minus 543) and the start years of Japanese eras. Check the start of the year in a reference for exact dates.
Standard scientific values, such as constants, atomic weights and melting points, are facts found in every textbook; we name where ours were checked. If you are an author or publisher and want a value, a credit or a table changed or removed, tell us and we will act quickly.
Last updated 2026-11-10.