Roman date tool
Roman numerals date converter
Enter a Gregorian date to see its standard Roman numeral form, or parse a Roman numeral date back to Gregorian. For example, 2026 is MMXXVI.
Date to Roman numerals
Roman date
MMXXVI.XI.II
Parse Roman numerals
Parsed date
2026-11-02
Strict mode rejects forms such as IIII, VV, IC, and repeated subtractive pairs.
Worked example: 29 February 2024 becomes XXIX.II.MMXXIV
Take the leap day of 2024 and convert each part separately. The day, 29, is XXIX: two tens (XX) followed by nine (IX). The month, February, is simply II. The year splits into MM for 2000, XX for 20, and IV for 4, giving MMXXIV. Joined with periods in day.month.year order the result is XXIX.II.MMXXIV; the same date in year.month.day order reads MMXXIV.II.XXIX, and month.day.year gives II.XXIX.MMXXIV.
The reverse direction checks the calendar, not just the numerals. Paste XXIX.II.MMXXIV and it parses cleanly because 2024 is a leap year. Change the year to MMXXV and the parser refuses it: February 2025 has only 28 days, so a 29th does not exist. The same rule catches XXXI.IV.MMXXVI, since April never reaches a 31st.
Why dates appear as Roman numerals
Roman numeral dates are most familiar on copyright pages, end cards, and production credits. They turn a plain year such as 2026 into MMXXVI, giving a book, programme, or film a formal colophon style while still preserving the legal year. Publishers often use them as a visual convention rather than a different calendar: the date is still Gregorian, only the digits have changed.
British TV viewers also associate the style with the BBC convention of showing a copyright year in Roman numerals at the end of a programme. Film and television credits use the same trick because a compact Roman year can look less commercial than Arabic numerals and sits neatly with studio marks, rights notices, and archival slates.
Full dates need a little more care. Standard Roman numerals have no zero, so months and days are written from I to XII and I to XXXI, while years are normally limited to I through MMMCMXCIX. This converter uses subtractive notation, so 4 is IV, 9 is IX, 40 is XL, 90 is XC, 400 is CD, and 900 is CM. The reverse parser rejects casual alternatives such as IIII or VV, which keeps copied copyright-page dates consistent.
The thirteen building blocks
Seven symbols carry all the value, and six fixed subtractive pairs handle the awkward numbers just below a threshold. Everything the converter outputs is a greedy combination of these thirteen parts, largest first.
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1,000 |
| Subtractive pair | Value |
|---|---|
| IV | 4 |
| IX | 9 |
| XL | 40 |
| XC | 90 |
| CD | 400 |
| CM | 900 |
What the strict parser refuses, and the reasons behind it
Three layers of validation run on every parse. The first is symbol-level: no numeral may repeat more than three times, so IIII and MMMM both fail, and only the six listed subtractive pairs are legal, which rules out inventions like IC for 99. The second layer is a round trip: the parsed value is re-encoded and must reproduce the input exactly, so any string that reaches the right number by a nonstandard route is discarded. The third layer is the calendar itself: months must fall in I to XII, days must exist in the given month and year, and years must stay within I to MMMCMXCIX.
Strictness is the point. A date meant for a copyright page or an inscription will be read by people applying the standard rules, so a permissive converter that accepts sloppy input would happily produce output others cannot verify. If a numeral you found in the wild fails to parse here, that is useful information: it was written outside the standard form.
Roman numeral date FAQ
What is 2026 in Roman numerals?
MMXXVI. Break it apart as MM for 2000, XX for 20, and VI for 6. A 1976 copyright reads MCMLXXVI: M for 1000, CM for 900, LXX for 70, VI for 6.
Why does the converter stop at the year 3999?
Standard notation caps each symbol at three repeats, so the largest expressible number is MMMCMXCIX, or 3999. Romans wrote larger values with an overline called a vinculum that multiplied a numeral by 1,000, but plain text cannot carry that mark reliably.
Why is IIII rejected when clock faces use it?
Watch and clock dials keep IIII by a long decorative tradition, but subtractive notation writes 4 as IV. The parser enforces the subtractive standard because that is what copyright pages, screen credits, and reference tables use.
Which part order should I choose?
Match the publication you are copying from. Screen credits and copyright pages usually carry the year alone, so any order works and you read the year segment. Full day.month.year dates in the dmy order are the usual choice on plaques and formal documents.
Can the tool convert dates before year 1?
No. Roman numerals have no zero and no negative values, so the converter covers years I through MMMCMXCIX, which is 1 through 3999 in the Common Era.