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: 1-20, 1-100, 101-200, 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:
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:
|1000s||MMM||1000 + 1000 + 1000||3000|
|100s||CD||500 - 100||400|
|10s||LX||50 + 10||60|
|1s||II||1 + 1||2|
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:
|2||2000||1000 + 1000||MM|
|3||300||100 + 100 + 100||CCC|
|4||40||50 - 10||XL|
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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Roman numerals: Value expression system that uses letter symbols for counting and representing numeric values (I, II, III, IV, V, etc.) instead of numeric characters.
Arabic numbers: The counting and value expression system we are accustomed to, which uses numeric characters (1, 2, 3, 4, 5, etc.).
Arabic number or Roman numeral entry field: Enter either an Arabic number or a Roman numeral (leave no spaces before, within, or after numbers or numerals). Please note that the Roman numeral converter currently only accepts Arabic numbers up to 3999, and Roman numerals up to MMMCMXCIX.
Translation result field: This is the Arabic number or Roman numeral translation -- depending on which type you entered in the top of the Roman Numeral Converter.
Printable Roman Numeral Chart button: If you would like to print out a Roman numerals chart, enter the starting Arabic number in the From field and the ending Arabic number in the To field and click this button. Upon doing so, a new, printer friendly window will open displaying your custom Roman Numeral Chart. Note that the chart will be five columns wide, so try to enter spans that are divisible evenly by 5 (1-20, 1-100, 101-200, etc.).