Roman Numeral Converter
Convert numbers to Roman numerals or Roman numerals to numbers. Bidirectional, with component breakdown.
Number to Roman Numeral
Roman Numeral to Number
Basic Roman Numerals
Roman Numeral Converter and Calculator
The Roman numeral converter tool helps you easily understand the Ancient Roman number system that we still frequently encounter on clocks, book pages, and historical documents. You can use this practical tool to convert a number to Roman numerals or to translate seemingly complex symbols (I, V, X, L, C, D, M) back into familiar digits.
How Are Roman Numerals Written and Read?
Roman numerals are built on seven basic letter symbols: I (1), V (5), X (10), L (50), C (100), D (500), and M (1000). These numerals are placed side by side to form new numbers using addition or subtraction logic. For example, a smaller numeral written to the right of a larger one is added (VI = 6), while one written to the left is subtracted (IV = 4).
The Subtraction Principle and Writing Rules
In the Roman numeral system, a symbol can appear side by side at most three times. The subtraction method is used to express numbers like 4 or 9. I can only be subtracted from V and X, X only from L and C, and C only from D and M.
Core Symbols
| Number | Roman |
|---|---|
| 1 | I |
| 4 | IV |
| 5 | V |
| 9 | IX |
| 10 | X |
| 40 | XL |
| 50 | L |
| 90 | XC |
| 100 | C |
| 400 | CD |
| 500 | D |
| 900 | CM |
| 1000 | M |
Roman Numeral Symbols and Values
Each letter in the system has a fixed numerical value. I=1, V=5, X=10, L=50, C=100, D=500 and M=1000. To express larger numbers, a horizontal line is drawn over the letters; this indicates that the value of that symbol is multiplied by 1,000.
Roman Numeral Writing Rules
A smaller symbol placed to the right of a larger one: add.
A smaller symbol placed to the left of a larger one: subtract.
The same symbol may be written at most 3 times in a row.
Use IV for 4 and IX for 9. IIII is not valid.