I was looking for a word that describes someone who is an expert in or studies calendars, and I couldn't find anything.

For more context, I am looking for the word you would call someone who knows how to calculate the number of days between a date in the distant past, when different calendars were used, and a date in the modern calendar. I thought historian, but I'm not sure that's adequate.

  • There isn't a specific word that I've ever heard. I think historian is adequate, though calendar historian might ring true.
    – Daniel
    Commented Mar 6, 2012 at 17:38
  • A reasonable attempt would be 'calendrist' or 'calendarist' except that actually refers to a use of a particular calendar, e.g. an Old Calendrist is one who, for political reasons, paid heed to the Julian calendar after the Gregorian calendar was instituted.
    – Mitch
    Commented Mar 6, 2012 at 18:29

7 Answers 7


I believe that you are looking for a horologist. (Horology: the art or science of measuring time.)

  • -1: horologist watchmaker: someone who makes or repairs watches. I know there are such things as "perpetual calendar" watches/clocks, but horology is really concerned with a different order of time. Commented Mar 6, 2012 at 20:33
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    Keep reading on your linked page and you will see "the science of measuring time", "technology of timekeeping", and other more general definitions. There does seem to be a bent toward mechanical timepieces specifically, but day/week/year ranges certainly fall within the purview of "time measurement".
    – Hellion
    Commented Mar 6, 2012 at 20:38
  • You can't just "bend" the definition that way - it's like saying ""simplify and "facilitate" mean the same thing just because their definitions overlap. Horologists deal with devices measuring hours - not days, years, or (in OP's context) centuries and millennia. Commented Mar 6, 2012 at 20:45
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    Horology is the study of means of measuring time and encompasses all means of measuring time, including both watches and calendars. Horology covers devices measuring anything from nanoseconds to eons. Commented Mar 6, 2012 at 20:58

Well, at least a couple of dozen people have been prepared to go into print with calenderologist and/or calenderology. So even though I don't think you'll find them in any dictionary, I guess these are the best words you'll get.

Sticking to words that are in the dictionary, chronology is the science that deals with the determination of dates and the sequence of events. So OP might want to go with chronologist.

EDIT: I didn't have access to the full (subscriber-only) OED when I wrote this answer. But now I have, I should just flag up these entries...

calendarer - One who calendars (esp. documents)
calendarian - A maker of a calendar
calendariographer - A calendar- or almanac-maker
calendarist - One who calendars (events, days, etc.), one who assigns dates and periods
calendary - Of, pertaining to, or according to, the calendar OR The act of calendaring

Spoilt for choice, really.


Wikipedia has this to offer, with a citation to a 1913 Webster's.

Chronometry (from Greek χρόνος "time" and μέτρηση "measurement") is the science of the measurement of time, or timekeeping. It should not to be confused with chronology, the science of locating events in time, which often relies upon it.

  • And so the person who does this a 'chronometrician'?
    – Mitch
    Commented Dec 12, 2016 at 20:51

The honest answer is that there is no commonly accepted word for the study of calenders. It's clear that the question relates to how societies perceive and describe the division of, and the progression of time. This involves in all cases the study and measurement of natural periodicity (astronomical generally) and in most cases is combined with the study and ordering of events (usually human or geological). For example the Roman calender measured time in years (astronomically-based) passed since the founding of Rome (event-based).

The science of the measurement of time is 'chronometry' (from the Latin/Greek words for 'time' and 'measurement') while the study of the ordering of events is 'chronology'(from the Latin/Greek words for 'time' and 'description'. A candidate word for the study of both might be 'chrononomy' (from the Latin/Greek words for time and arrangement). The Oxford English Dictionary recognizes 'chrononomy' but describes its (historical) use as rare. Hovever this only reflects the fact that the study of calendars is a very modern interest.

'Horology' comes from the Latin/Greek words for hour and description, but has come to (generally) relate to the study of mechanisms for measuring time. It has to be said that the Greek word here also included a sense of seasons and time generally, but the Latin word definitely relates to hours.

Calendar comes from the Latin word Calends, meaning 'call' or 'proclaim', and used uniquely in Rome in relation to the first day of each month. The first day of each Roman month was a day on which announcements would be made, and accounts would be calculated from. Strictly speaking then, the word 'calendology' would mean something like the study of proclamation descriptions. Words, however, mean whatever we mean them to mean, and 'calendology', or 'calendarology' might work for us, even if the philologists shudder at it.

  • Thank you for posting John Mack, this is a very interesting read! Your answer could be helped by some references and/or links to the more obscure definitions (such as the meaning of 'calends' for the Romans), but it's nonetheless incisive and well written. +1.
    – 568ml
    Commented May 8, 2014 at 7:24

I agree with @Daniel δ that there isn't a specific term for this. But I believe the term calendar scholar is close to what you want to express.

A chronologist is someone who studies historical records to establish the dates of past events, so this term can be used if you are interested in this connotation.


Those who study calendars are most likely to be doing so as historians or archaeologists, as subdivisions of subjects such as astronomy or astrology, or religion, or of the specific cultures that produced the calenders. A good overview would be something like Calendars in Antiquity: Empires, States, and Societies by Sacha Stern (OUP, 2012). No answer to the specific question, I am afraid. Horologist probably comes closest, though in the past you would have called someone doing such calculations an astrologist!


A calendar scholar may have the requisite knowledge to perform these calculations, but then so do your or I or anyone. The conversions are not difficult computations, and the algorithms to make the conversions are fixed. There are many calculators for making the conversions found easily with google. My point is that the conversion of dates is hardly a mysterious power held by a few experts, hence a reference to a specific type of person who made the calculation is unnecessary. A historian could easily do it and I don't think there's need to highlight his ability as anything extraordinary.

  • Actually, they aren't that easily found on Google, because many of seem to wrongly account for calendar adjustments made in the antiquities.
    – Nicole
    Commented Mar 6, 2012 at 18:33
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    Doesn't address the question, though. It doesn't matter if it's the simplest thing in the world for people to do. That has no bearing on the (potentially hypothetical) nomenclature. Commented Mar 6, 2012 at 19:17
  • Certainly it does. To quote the OP "I am looking for the word you would call someone who knows how to calculate the number of days between a date in the distant past" and my point is that any number of types of people would fit that bill and any scholar of calendars while certainly capable of performing the task would, I think, but overqualified. Like having a Nobel economist doing your taxes.
    – Sam
    Commented Mar 7, 2012 at 1:13
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    You're seriously underestimating the many ways people have done calendars. Merely within the Roman tradition there have been a number of variants. Outside it I can rattle off the Chinese, Jewish, Mayan, and Islamic calendars, and I'm no ... "calendar scholar," as the best answer I've seen so far. I'm sure those just scratch the surface. Does the existence of Google Translate make linguists unnecessary?
    – user32047
    Commented Dec 19, 2012 at 12:27

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