Roman Numeral Converter

How to use the Roman Numeral Converter

1. Type a number in the Number box to see it as a Roman numeral, or type a numeral in the Roman numeral box to see its value. Both update as you type.
2. Read the breakdown to see how thousands, hundreds, tens and ones combine.
3. If a numeral is not standard, read the explanation and click the suggested correction.
4. To convert a date, pick it below, choose the order and separator, and copy the result.

Features

• Converts both directions as you type
• Strict validation with plain-English explanations
• Place-by-place breakdown, e.g. M + CM + XC + IV
• Vinculum notation for numbers above 3,999
• Dates in US, European or ISO order
• One-click copy for numerals and dates

The seven symbols

Every Roman numeral is built from these seven letters. The modern standard form, the one taught in schools and used on clocks, buildings and film credits, follows a few strict rules.

The rules of standard Roman numerals

1. Add when symbols stay the same or get smaller from left to right: VIII = 5 + 1 + 1 + 1 = 8.
2. Subtract when a smaller symbol comes before a larger one, but only in six pairs: IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900).
3. Repeat I, X, C and M at most three times in a row. Four is IV, not IIII.
4. Never repeat V, L or D, because two of them would simply be X, C or M.
5. Write each decimal place separately, largest first. That is why 99 is XCIX (90 + 9) and never IC.

Converting step by step

Split the number into thousands, hundreds, tens and ones, convert each part and join them. For 1994: 1000 = M, 900 = CM, 90 = XC and 4 = IV, giving MCMXCIV. For 2026: 2000 = MM, 20 = XX and 6 = VI, giving MMXXVI. Reading a numeral works the same way in reverse; the breakdown above shows each part.

Why the standard stops at 3,999

With M as the largest symbol and a limit of three repeats, MMMCMXCIX (3,999) is the biggest number the standard form can write. For larger values the Romans and later scribes used a vinculum, a bar over a numeral that multiplies it by 1,000, so V̅ means 5,000 and X̅ means 10,000. This converter shows the vinculum form for numbers up to 3,999,999 as a reference, but it is a historical convention rather than part of the everyday standard. There is also no Roman numeral for zero; medieval writers who needed one used the word nulla.

Where you still see Roman numerals

• Clock faces, which often show four as IIII rather than IV, a long-standing design tradition.
• Names of monarchs and popes, such as Elizabeth II or Louis XIV.
• Book front matter, where prefaces are numbered i, ii, iii in lowercase.
• Film and TV copyright years, sporting events like the Super Bowl, and building cornerstones.
• Outlines and legal documents, where sections are numbered I, II, III.

Dates in Roman numerals

Each part of a date is converted separately and joined with a separator. The US order puts the month first: 4 July 1776 becomes VII.IV.MDCCLXXVI. In day-month-year order the same date is IV.VII.MDCCLXXVI. If the result is going on a tattoo, ring or engraving, check the order twice, because a reader in another country may interpret it differently. To see how many years have passed since an anniversary, try the Age Calculator, and to write numbers out in words, use the Number to Words Converter.

Frequently asked questions