Convert a number to Roman numerals, or a Roman numeral back to a number, instantly and both ways.
Roman numerals still turn up on clock faces, book chapters, movie credits, and monument dates, and reading or writing them correctly means remembering a set of letter values and the subtractive rules. This Roman Numeral Converter goes both ways, turning a regular number into its Roman form and a Roman numeral back into a number, so you never have to decode MCMXCIV by hand again.
You type a number to get the Roman numeral, or paste a Roman numeral to get the number, and the result appears instantly. The conversion runs live as you type, so you can experiment, and switching direction is as simple as entering the other kind of value. It is quick enough to use mid-task when you just need to check a single figure.
The system uses seven letters, I for 1, V for 5, X for 10, L for 50, C for 100, D for 500, and M for 1000, combined largest to smallest and added together, with a smaller letter before a larger one meaning subtraction. So four is IV, nine is IX, and forty is XL. As an example, 1994 becomes MCMXCIV, which reads as M for 1000, CM for 900, XC for 90, and IV for 4. The standard form covers numbers up to 3999, since there is no single letter for larger values.
Reach for this over doing it manually whenever the number is anything beyond the obvious, because the subtractive pairs like IX and XC are exactly where people slip, writing IIII instead of IV or misreading a year on a title card. Going the other way, decoding a long numeral by hand is error-prone in a way a converter simply avoids.
People use it to write a year in Roman numerals for a design or a tattoo, to decode the copyright date at the end of a film, to number book chapters or outline sections, and to help with a homework or a quiz question. Both directions get used about equally.
Everything happens in your browser. The values you enter are never uploaded, there is no sign-up, and nothing is stored after you close the tab, so the only limit is your device. Use it freely whenever a Roman numeral needs reading or writing.
Standard Roman numerals go up to 3999, written as MMMCMXCIX, because the classic system has no single symbol for values above M repeated three times. Numbers beyond that historically used bars over letters, which the everyday notation does not include.
No, the Roman system has no symbol for zero, since it was built for counting rather than positional place value. That is one reason it is awkward for arithmetic and was eventually replaced for calculation by the numerals we use today.
Standard notation uses the subtractive rule, placing a smaller I before V to mean one less than five. You do sometimes see IIII on clock faces as a stylistic choice, but the conventional written form is IV.
Roman numerals are conventionally uppercase, though the values of the letters are the same regardless of case. Enter them as the tool expects, and if it accepts lowercase it treats i, v, and x the same as their capitals.
A numeral that breaks the rules, such as too many repeats or a bad subtractive pair, is not a valid number and cannot be converted meaningfully. Double-check the letters against the standard values if the result looks wrong.
Break it into groups from the left, largest first, so M is 1000, CM is 900, LXXX is 80, and IV is 4, giving 1984. The converter does this for you, but grouping by value is how you would decode it by hand.
No, the classic system deals only with positive whole numbers, so fractions and negatives are outside its scope. The Romans did use a separate fractional notation, but it is not part of the standard numerals this tool converts.
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