Numbers to Roman numerals and back, with a check that says why a numeral is wrong
Runs in your browser. Nothing you type is sent anywhere. Updated on 25 Oct 2026.Standard Roman numerals cover 1 to 3,999 with seven letters, I, V, X, L, C, D and M, and six subtractive pairs such as IV and CM. So 1994 is MCMXCIV and 2026 is MMXXVI. A strict converter rejects forms like IIII, VX and IC and says which rule each one breaks.
Type a number from 1 to 3,999, or a Roman numeral, in the Number or Roman numeral box.
Read the result, with the symbols that build it shown underneath.
Turn on "Overline for 4,000 and up" for larger numbers, a convention rather than the standard form.
Press Copy, or Ctrl+Enter, to take the result.
The Roman Numeral Converter works in both directions from one box. Type a number such as 1994 and you get MCMXCIV, broken into its pieces, M + CM + XC + IV, and their values, 1,000 + 900 + 90 + 4. Type or paste a numeral in capitals or lower case and you get the number back.
Checking is strict, because the point of a converter is often to catch a mistake before it is printed or engraved. A numeral is accepted only in its standard form, and when it is not, the tool names the rule it breaks. IIII is refused because I repeats at most three times, and the page mentions that clock faces use IIII by custom. VX is refused because V, L and D are never subtracted. IC is refused because I is subtracted only from V and X, and the tool suggests XCIX for 99. VV, symbols out of order and letters that are not numerals each get their own message.
Dates are converted part by part. Type 29.9.2026, or use the date fields, and get XXIX.IX.MMXXVI, with a choice of day-month-year, month-day-year or year-month-day and five separators. Impossible dates such as 29 February in a year that is not a leap year are refused. Paste a Roman date back to read it.
Standard numerals stop at 3,999 because there is no standard sign for 5,000. Some medieval writers put a bar over a numeral to multiply it by 1,000. That overline notation is available here as a switch, labelled as a convention rather than a standard, for numbers up to 3,999,999; it is written with a combining overline character, which some fonts draw poorly.
What it does not do: there is no zero, no negative numbers and no fractions, and it does not read the older additive styles found on some ancient inscriptions. Everything runs in your browser.
Type the number, from 1 to 3,999, and the numeral appears as you type with its pieces shown underneath. The method is to take the largest value that fits, from M 1000, CM 900, D 500 down to I 1, write its symbol and repeat with what is left. 1994 becomes M, CM, XC, IV.
Not in the standard form, where 4 is IV and no symbol repeats more than three times in a row. Many clock and watch faces show IIII anyway, a clockmakers' custom often said to balance the dial against VIII. The converter explains this when IIII is typed and suggests IV.
Subtraction is allowed only from the next two larger symbols: I from V and X, X from L and C, and C from D and M. So 99 is 90 plus 9, XC plus IX, which gives XCIX. Forms like IC, IL and XM are refused with the correct spelling suggested.
Standard numerals end at 3,999, written MMMCMXCIX, because there is no standard single sign for 5,000. A bar over a numeral, called a vinculum, was later used to mean times 1,000. Switch on overline notation to write numbers up to 3,999,999 that way, knowing it is a convention and not a fixed rule.
Convert the day, month and year separately and join them with dots or another separator. 29 September 2026 is XXIX.IX.MMXXVI in day-month-year order. The date fields on this page do that for you, check the date exists, and let you choose the order and the separator before you copy it.
No. The Roman system had no symbol for zero. Around the 8th century some writers used the word nulla, meaning none, or its first letter N, in tables. The converter says so when 0 is typed, and it also refuses negative numbers and fractions, which the standard form cannot express.
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Also works as: Roman Numeral Year Converter.