Roman Numeral Converter
Convert numbers to Roman numerals and Roman numerals back to numbers, with the rules that govern them.
Roman numerals use seven symbols: I is 1, V is 5, X is 10, L is 50, C is 100, D is 500 and M is 1,000. Values add left to right, except that a smaller symbol placed before a larger one subtracts, which is why IV is 4 and IX is 9.
By Piero Nanni · Last checked
Roman Numeral Converter
Roman numerals are a sign-value system rather than a positional one. In 2,026 the 2 means two thousand because of where it sits; in MMXXVI the two Ms mean a thousand each wherever they appear. That is what makes the system easy to read and awkward to calculate with, and why it survived for labelling, dates and chapter numbers long after it stopped being used for arithmetic.
The subtractive rule is the part that trips people. Only I, X and C can be subtracted, and only from the next two symbols up: I before V or X, X before L or C, C before D or M. So 99 is XCIX, ninety plus nine, not IC. Clock faces that show IIII for four are following an older additive convention, not making a mistake.
The seven symbols
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1,000 |
Numbers 1 to 20
| Number | Roman numeral |
|---|---|
| 1 | I |
| 2 | II |
| 3 | III |
| 4 | IV |
| 5 | V |
| 6 | VI |
| 7 | VII |
| 8 | VIII |
| 9 | IX |
| 10 | X |
| 11 | XI |
| 12 | XII |
| 13 | XIII |
| 14 | XIV |
| 15 | XV |
| 16 | XVI |
| 17 | XVII |
| 18 | XVIII |
| 19 | XIX |
| 20 | XX |
Tens, hundreds and thousands
| Number | Roman numeral |
|---|---|
| 30 | XXX |
| 40 | XL |
| 50 | L |
| 90 | XC |
| 100 | C |
| 400 | CD |
| 500 | D |
| 900 | CM |
| 1,000 | M |
| 1,500 | MD |
| 1,900 | MCM |
| 2,000 | MM |
| 3,999 | MMMCMXCIX |
How to write a number in Roman numerals
Work from the largest symbol down. Take out as many thousands as fit, then hundreds, then tens, then units, writing the standard form for each digit. 1,984 is 1,000 plus 900 plus 80 plus 4, which is M, CM, LXXX, IV, giving MCMLXXXIV.
No symbol repeats more than three times in standard form, which is what the subtractive pairs exist to prevent. Forty is XL rather than XXXX, and nine hundred is CM rather than DCCCC. Where you see four repeats on a monument or a clock, it is a deliberate stylistic choice rather than the standard form.
Why the system stops at 3,999
M is the largest single symbol, and three is the repeat limit, so MMM at 3,000 plus CMXCIX at 999 is as far as standard notation reaches. Anything above needs an extension.
The historical extension is the vinculum, a bar over a numeral multiplying it by a thousand, so a barred V is 5,000 and a barred X is 10,000. It is rarely used today outside academic transcription, and no widely supported plain-text convention replaced it, which is why most converters simply cap at 3,999.
Where you still meet them
Copyright dates in film and television credits, monarch and pope regnal numbers, Super Bowl numbering, book preface pagination, clock faces, building cornerstones and the numbering of world wars. Almost all of these fall well inside the 3,999 limit.
The one genuinely modern use is outline numbering, where I, II, III mark top-level sections above A, B, C and 1, 2, 3. There the numerals are doing what they are good at: being visually distinct from ordinary numbers at a glance.
Frequently Asked Questions
What is 2026 in Roman numerals?
2026 is MMXXVI: two thousands, two tens, a five and a one.
Why is 4 written IV and not IIII?
The subtractive rule puts a smaller symbol before a larger one to subtract it, avoiding four repeats. Clock faces often use IIII by tradition.
What is the largest Roman numeral?
In standard notation, 3,999, written MMMCMXCIX. Larger values need a bar over a symbol to multiply it by a thousand.
Is there a zero in Roman numerals?
No. The system has no symbol for zero and no positional places that would need one.
What is 1984 in Roman numerals?
1984 is MCMLXXXIV.