This free online numeral calculator will convert Roman numerals into Arabic numbers and visa versa, plus display a conversion chart showing exactly how it arrived at the translation.
Plus, unlike other online conversion calculators, if you enter an invalid Roman numeral, the calculator on this page will even alert you to which rule or rules were broken by your entry.
Finally, the Roman numeral converter also provides a feature that will allow you to create your own custom, printable Roman numerals chart: 120, 1100, 101200, or whichever span of numbers you choose. Cool!
The first step in learning how to read Roman numerals is to familiarize yourself with the Arabic value represented by each letter  which can be seen in the following chart:
1  5  10  50  100  500  1000 
I  V  X  L  C  D  M 
The next step in learning how to read Roman numerals is to become aware of how the placement of numerals impacts the translated value. In that regard, there are two rules you need to be aware of when attempting to translate the numerals into values:
The following conversion chart shows how you would read the Roman numeral "MMMCDLXII"  which includes instances of both addition and subtraction:
Place Value 
Roman Numerals 
Addition/Subtraction  Arabic Numerals 
1000s  MMM  1000 + 1000 + 1000  3000 
100s  CD  500  100  400 
10s  LX  50 + 10  60 
1s  II  1 + 1  2 
Totals  MMMCDLXII  =  3462 
In addition to the rules you have learned for reading Roman numerals, there are a few more rules you need to know when writing Roman numerals.
With the above rules in mind, here is how you would write the Roman numeral for the Arabic number 2345:
Digit  Place Value 
Addition/Subtraction  Roman Numerals 
2  2000  1000 + 1000  MM 
3  300  100 + 100 + 100  CCC 
4  40  50  10  XL 
5  5  5  V 
Totals  2345  =  MMCCCXLV 
With that, let's use the Roman Numeral Converter to translate to and from Arabic numbers, or to create a custom, printable Roman numeral chart.

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