Engineering
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
I = 1V = 5X = 10L = 50C = 100D = 500M = 1000
Roman Numerals: A 2,000-Year-Old Number System
Roman numerals are a seven-symbol number system that has survived from ancient Rome to the present day: I, V, X, L, C, D and M. We still encounter them in modern life — from clock faces to film production years, Olympic Games to royal titles. This tool works bidirectionally: convert numbers to Roman numerals and Roman numerals back to numbers.
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 Writing Rules
AdditiveVI = 5+1 = 6
A smaller symbol placed to the right of a larger one: add.
SubtractiveIV = 5−1 = 4
A smaller symbol placed to the left of a larger one: subtract.
RepetitionIII = 1+1+1 = 3
The same symbol may be written at most 3 times in a row.
ExceptionIV — IIII
Use IV for 4 and IX for 9. IIII is not valid.
Roman Numerals in Everyday Life
- Film & TV: Production years appear in credits as Roman numerals (MMXXVI = 2026).
- Clock faces: Analogue clocks often display 1–12 in Roman numerals; both IV and IIII are used for 4.
- Olympic Games: Each Olympiad is referred to by its number in Roman numerals (XXXIII Paris Olympics 2024).
- Monarchy & religion: Titles such as Elizabeth II, Benedict XVI.
- Books & documents: Preface pages are often numbered i, ii, iii (lowercase) in Roman numerals.
Things to Watch Out For
- The standard Roman numeral system covers 1–3999. Numbers 4000 and above require extended notation.
- IIII appears on some antique clock faces in place of IV; the modern standard accepts IV.
- Doubled symbols such as VV, LL, DD are invalid; use X, C, M instead.
- Lowercase Roman numerals (i, ii, iii…) are used for page numbering; the mathematical value is the same.