Reference Centre, Calendars-Calculators

Roman Numeral Calculator

During the 16th, and into the 17th centuries, Roman numerals were used almost entirely throughout Britain in place of our now everyday Arabic numbering system.  Roman numerals were used to date parish registers, Wills, and land records.  Roman numerals were also used to express monetary values on tax, inventory and other court documents.  Many people, today, have lost the art of quickly deciphering Roman numerals, especially as those numbers reach into the high tens, hundreds and thousands.

Additionally, the Roman numeral system used in Britain prior to the mid-1700s contained a few anomalies with which most people are unfamiliar.  For example, what appears to be "iiij" on a document is really "iiii" which we would know, today, as being "iv" or Arabic numeral 4.  Similar anomalies will be encountered in the expression of a year.  For example, "MCCCCC" is what we would know today as being "MD" or Arabic numeral 1500.

Because I am all too acutely aware of the difficulties many researchers have with Roman numerals, I have searched for an apt conversion tool - one that will allow a researcher to enter an "old-style" Roman numeral and still be able to obtain a correct value.  The Roman Numeral converter boxes, below, allow for just such occasions.

Instructions for Use

There are three separate entry boxes below. If you believe you have an "old style" Roman numeral, enter that number in the bottom most box.  Click on the "Convert" button next to it.  The correct Roman numeral expression will be displayed in the box immediately above it.  Then, click on the "Convert" button next to that second box and the translation into a decimal or Arabic number will be displayed in the top-most box.

If you believe you have a correctly formed Roman numeral, simply enter that sequence into the second box and click on the "Convert" button next to it.  If it is not a correctly formed Roman numeral you will receive an "Input Error" message in the top box.  If this happens, simply click on the "Reset" button next to the third box and re-enter your Roman numeral sequence in that box and proceed as described in the paragraph above.

Decimal:

Roman:

Enter an old-style Roman Numeral here, e.g. viiii rather than modern-style Roman numeral ix:

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