Convert between Arabic numbers and Roman numerals. Also supports date conversion and large numbers with vinculum notation.
Roman numerals originated in ancient Rome and were used throughout the Roman Empire. They are still used today in certain contexts, such as on clock faces, in book chapters, for numbering events like the Olympics and Super Bowl, and in formal documents.
The Roman numeral system uses combinations of letters from the Latin alphabet to signify values. Unlike our modern Arabic numeral system, Roman numerals do not use a zero, and their values are based on addition and subtraction principles.
| Roman Numeral | I | V | X | L | C | D | M |
|---|---|---|---|---|---|---|---|
| Arabic Number | 1 | 5 | 10 | 50 | 100 | 500 | 1,000 |
When a smaller or equal numeral appears after a larger one, add the values.
Examples: VI = 6, XII = 12, CL = 150
When a smaller numeral appears before a larger one, subtract the smaller from the larger.
Examples: IV = 4, IX = 9, XL = 40, CD = 400, CM = 900
Only I, X, C, and M can be repeated. V, L, and D cannot be repeated. No numeral can be repeated more than three times consecutively.
Examples: III = 3, XXX = 30, but not IIII or VV
Only I, X, and C can be used as subtractive numerals, and only before the next two higher numerals.
Valid: IV, IX, XL, XC, CD, CM
Invalid: VX, LC, DM
For numbers larger than 3,999, Romans used a vinculum (overline) to multiply by 1,000. In this converter, use an underscore (_) before the numeral to indicate vinculum.
| Roman with Vinculum | I | V | X | L | C | D | M |
|---|---|---|---|---|---|---|---|
| Arabic Number | 1,000 | 5,000 | 10,000 | 50,000 | 100,000 | 500,000 | 1,000,000 |
| Converter Input | _I | _V | _X | _L | _C | _D | _M |
Break down by place value:
1000 = M
900 = CM
90 = XC
4 = IV
Result: 1994 = MCMXCIV
Break down each component:
MM = 2000
XX = 20
V = 5
Result: MMXXV = 2000 + 20 + 5 = 2025
| Day | Roman Numeral |
|---|---|
| Monday | I |
| Tuesday | II |
| Wednesday | III |
| Thursday | IV |
| Friday | V |
| Saturday | VI |
| Sunday | VII |
Roman numerals were widely used throughout the Roman Empire and continued to be the primary number system in Europe until Arabic numerals were introduced in the 14th century. Today, Roman numerals are still used in formal contexts, movie sequels, clock faces, and to denote important events or publications.
Understanding Roman numerals provides insight into historical documents and remains useful for reading traditional timepieces, architectural inscriptions, and formal publications. This converter helps bridge the gap between ancient and modern numbering systems.