Convert numbers and years to Roman numerals — and back
This Roman numeral converter works in both directions at once: type a number to see it in Roman numerals, or type a numeral such as MCMXCIV to see its value. It covers every standard numeral from 1 to 3,999 and, with large numbers switched on, goes all the way to 3,999,999 using the vinculum — the bar that multiplies a numeral by 1,000.
Unlike simple translators, it checks numerals strictly. Write IIII, VX or IC and it explains exactly which rule is broken and gives the correct form. A place-value breakdown shows how each numeral is built, which makes it useful for homework, tattoos, film credits, building cornerstones, book chapters and Super Bowl trivia alike.
How to use the Roman Numeral Converter
- Type a whole number in the “Number” box — the Roman numeral appears instantly in the second box and in large type below.
- Or type a Roman numeral (capitals or lowercase) in the “Roman numeral” box to get its value.
- Tap a year shortcut, such as “This year”, to convert common dates in one click.
- For numbers of 4,000 or more, tick “Large numbers”. To type a barred letter yourself, put an underscore in front of it: _X means X̅ = 10,000.
- Check the place-value breakdown, then copy the numeral or the number with the buttons.
Roman Numeral Converter features
Two-way conversion
Number to Roman and Roman to number in the same view, updating as you type.
Strict validation with reasons
Invalid numerals are rejected with a clear rule — too many repeats, illegal subtraction or wrong order — plus the correct spelling.
Up to 3,999,999
The vinculum (overline) notation extends Roman numerals beyond MMMCMXCIX, clearly labelled so it is not confused with standard numerals.
Place-value breakdown
See each thousands, hundreds, tens and ones part, its value and how it is formed, e.g. 1994 = M + CM + XC + IV.
Year shortcuts
Convert this year and famous years in one tap — handy for copyright dates and anniversaries.
Roman numeral symbols and rules
Roman numerals use seven letters: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1,000. A number is written from the largest value to the smallest, and the values are added: VIII = 5 + 1 + 1 + 1 = 8, and MDCLXVI = 1,666.
To avoid four identical symbols in a row, six subtractive pairs place a smaller symbol before a larger one: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400 and CM = 900. Only I, X and C may be subtracted, and only from the next two larger symbols — so 99 is XCIX, never IC, and 49 is XLIX, never IL.
- I, X, C and M may repeat up to three times in a row (III, XXX, CCC, MMM).
- V, L and D are never repeated and never subtracted.
- Only one symbol may be subtracted at a time: 8 is VIII, not IIX.
- Each place value (thousands, hundreds, tens, ones) is written separately, then joined: 1994 = M + CM + XC + IV.
| Number | Roman | Number | Roman |
|---|---|---|---|
| 1 | I | 40 | XL |
| 4 | IV | 50 | L |
| 5 | V | 90 | XC |
| 9 | IX | 100 | C |
| 10 | X | 400 | CD |
| 14 | XIV | 500 | D |
| 19 | XIX | 900 | CM |
| 20 | XX | 1,000 | M |
Writing years in Roman numerals
Years are the most common use of Roman numerals today, from film copyright lines to graduation rings. Convert each part separately and join them: 2026 = 2000 + 20 + 6 = MM + XX + VI = MMXXVI. Years in the 1900s begin with MCM, which is why 1999 is MCMXCIX and 1984 is MCMLXXXIV. The year 2000 is simply MM, and 1066, the Battle of Hastings, is MLXVI.
If you need the day of the week for a historical date, the day of the week calculator can help, and the number to words converter spells the same year out in English.
| Year | Roman numeral | Year | Roman numeral |
|---|---|---|---|
| 1776 | MDCCLXXVI | 2000 | MM |
| 1900 | MCM | 2010 | MMX |
| 1950 | MCML | 2020 | MMXX |
| 1990 | MCMXC | 2025 | MMXXV |
| 1999 | MCMXCIX | 2030 | MMXXX |
Numbers above 3,999: the vinculum
Standard Roman numerals stop at 3,999 because M may only be repeated three times. For larger values, medieval and later writers drew a bar (a vinculum) over a numeral to multiply it by 1,000: V̅ = 5,000, X̅ = 10,000, C̅ = 100,000 and M̅ = 1,000,000. So 4,800 is I̅V̅DCCC and 3,999,999 is M̅M̅M̅C̅M̅X̅C̅I̅X̅CMXCIX. Ancient Romans actually used several different systems for big numbers, so the bar form is a later convention rather than a single official rule. This converter uses it consistently and marks it clearly.
Roman Numeral Converter FAQ
How does the Roman numeral converter handle invalid numerals?
It checks every numeral against the standard rules. If a numeral breaks one — such as IIII, VX, IC or IIX — it explains the rule that is broken and shows the correct numeral for the value its symbols add up to.
What is 2026 in Roman numerals?
2026 is MMXXVI: MM for 2,000, XX for 20 and VI for 6.
Why is 4 written IV and not IIII?
The standard rule allows a symbol to repeat at most three times, so 4 uses subtraction: one before five, IV. Some clocks and watches show IIII for visual balance, but IV is the accepted form in writing.
Is there a Roman numeral for zero?
No. The Roman system had no symbol for zero. Around the 8th century, some scholars used the word nulla, or simply N, in tables, but it was never part of the numeral system.
What is the largest Roman numeral?
Without extra notation, the largest standard numeral is MMMCMXCIX = 3,999. Using a bar to multiply by 1,000, numbers up to 3,999,999 can be written, which is the limit of this converter.
How do I type a Roman numeral with a line over it?
In this converter, type an underscore before the letter: _V becomes V̅ (5,000). In other documents, the bar is the Unicode combining overline (U+0305) placed after each letter.