Roman Numeral Converter

Convert Numbers to Roman Numerals and Back

The Tools Kit’s free Roman Numeral Converter works in both directions on one page: type a number to get its Roman numeral, or type a Roman numeral to read it as a number. Results update as you type, there is no button to press, and each answer has its own Copy button. It handles whole numbers from 1 to 3999 and always writes the standard subtractive form, so 4 comes out as IV and 900 as CM.

Use it to translate a year for a tattoo, wedding date or film credit, check a clock face or building inscription, or number chapters and outline sections. Both conversions run in your browser, so nothing you type is sent anywhere.

How to Use the Roman Numeral Converter

1. 1

   Type a number

   Enter a whole number from 1 to 3,999,999 in the Number box. The Roman numeral appears below it as you type, with a bar over the thousands for numbers above 3,999.

2. 2

   Or type a Roman numeral

   Use the Roman Numeral box to go the other way. Upper or lowercase letters both work, as long as you use only I, V, X, L, C, D and M.

3. 3

   Or pick a date

   Use the Date box to write a whole date in Roman numerals. Choose the order of day, month and year, and the separator between them.

4. 4

   Read the result

   Every box updates instantly and works independently, so you can convert in any direction without clearing the others.

5. 5

   Copy what you need

   Each result has its own Copy button, so you can paste just the numeral or just the number into a document, caption or design.

Roman Numeral Letters and Their Values

Roman numerals are built from seven letters. Every number is a combination of these.

How Roman Numerals Work

Letters are written largest to smallest and their values added: LXVI is 50 + 10 + 5 + 1 = 66. The exception is subtractive notation: when a smaller letter comes before a larger one, it is subtracted instead. That is why 4 is IV (5 − 1) and 9 is IX (10 − 1), and why XXIV reads as 10 + 10 + (5 − 1) = 24.

Only I, X and C are used subtractively, and only before the next two larger values. That gives six standard pairs (IV, IX, XL, XC, CD and CM), and it is why 99 is XCIX rather than IC and 49 is XLIX rather than IL. Classical Roman numerals also have no zero and no way to write numbers above 3,999 without an overline, which is why the converter switches to overline notation there.

Worked Examples: Number to Roman Numeral

To convert a number to Roman numerals, split it into thousands, hundreds, tens and ones, then write each part with the largest symbols that fit. This is exactly what the converter does, working through the thirteen values M, CM, D, CD, C, XC, L, XL, X, IX, V, IV and I from largest to smallest.

• 1984 = 1000 + 900 + 80 + 4 = M + CM + LXXX + IV = MCMLXXXIV
• 1999 = 1000 + 900 + 90 + 9 = M + CM + XC + IX = MCMXCIX
• 444 = 400 + 40 + 4 = CD + XL + IV = CDXLIV
• 3999 = 3000 + 900 + 90 + 9 = MMM + CM + XC + IX = MMMCMXCIX, the largest value without an overline
• 12,345 = 12 thousand + 345 = X̅I̅I̅ + CCCXLV = X̅I̅I̅CCCXLV, with a bar over the thousands

Going the other way, read left to right and subtract any letter that sits before a larger one: MCMXCIX is 1000 + (1000 − 100) + (100 − 10) + (10 − 1) = 1999. If you need a number spelled out in English instead, the number to words converter writes 1999 as words, and the words to number converter turns written-out numbers back into digits.

How Strict Is the Roman Numeral to Number Check?

The Roman Numeral box accepts only the seven letters I, V, X, L, C, D and M, in upper or lowercase. Anything else, such as a digit, another letter or a space inside the numeral, shows an error. Beyond that, it applies the subtraction rule to whatever you type rather than enforcing standard spelling: IIII is read as 4, IC as 99, and MMMM as 4000, even though the standard forms are IV, XCIX and I̅V̅. It does not read overlines. When a spelling is not standard, the box says so and shows the standard form. This is useful for reading the IIII on a clock face, but if you need the correct spelling of a number, type the number into the Number box and copy the result.

Roman Numerals 1 to 20

Roman Numerals 30 to 100 (tens)

Roman Numerals 200 to 1000 (hundreds)

Years and Dates in Roman Numerals

2026 in Roman numerals is MMXXVI. To write a date in Roman numerals, convert each part separately: 14 February 2026 becomes XIV · II · MMXXVI. Keep the day, month and year in the order you normally write dates. Working out an anniversary or birthday first? The age calculator gives an exact age from a birth date, and the days calculator counts the days between two dates.

Common uses

• Converting a birth year, wedding date or anniversary for a tattoo, ring engraving or invitation
• Reading a copyright year in film and TV credits, or the date on a monument or building
• Numbering chapters, appendices, outline sections or the front-matter pages of a document
• Reading clock and watch faces, event names and royal or papal names such as Henry VIII
• Homework and teaching material on how the Roman numeral system works

Roman numerals are one of several ways to write the same number. For other systems, the binary converter moves numbers between binary, decimal, hexadecimal and octal, and the ASCII converter turns text into its decimal, hex and binary character codes. For dates stored by computers rather than carved in stone, the timestamp converter turns Unix timestamps into readable dates.

Roman numeral terms explained

Related converters

The Tools Kit has more free converters for numbers and units, including the unit converter for length, weight and temperature. Browse them all in the conversion tools hub.

• Number to words converter
• Words to numbers converter
• Binary converter
• ASCII converter

Frequently Asked Questions