Roman Numeral Converter
Numbers & DatesConvert integers from 1 to 3999 to Roman numerals and Roman numerals back to integers. Explains subtractive notation rules with a step-by-step breakdown.
Roman Numeral
MMXXVI
| Arabic | Roman | Arabic | 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 | 1776 | MDCCLXXVI |
| 2000 | MM | 2024 | MMXXIV |
| 2025 | MMXXV | 2026 | MMXXVI |
About Roman Numeral Converter
The Roman numeral converter translates any integer between 1 and 3999 to its Roman numeral representation and decodes any Roman numeral string back to a decimal integer. The tool uses standard subtractive notation — where IV means 4, IX means 9, XL means 40, XC means 90, CD means 400, and CM means 900 — as codified by the ISO 15924 conventions. Each conversion comes with an optional step-by-step breakdown showing exactly how the value is assembled from the seven classical symbols: I, V, X, L, C, D, and M.
Features
- ✓Convert any integer from 1 to 3999 to Roman numerals
- ✓Decode any valid Roman numeral string to its integer value
- ✓Step-by-step breakdown of how the conversion is assembled
- ✓Validation with helpful error messages for invalid Roman numeral input
- ✓Uppercase and lowercase Roman numeral output toggle
- ✓Quick-reference symbol table (I=1, V=5, X=10, L=50, C=100, D=500, M=1000)
- ✓Current year in Roman numerals displayed automatically
- ✓One-click copy of the result
Common Use Cases
- Convert a year to Roman numerals for a logo, film title, or monument inscription
- Decode chapter or section numbers in legal and academic documents
- Understand clock faces with Roman numeral hour markers
- Format Super Bowl or Olympic Games numbering (e.g., Super Bowl LVIII)
- Generate Roman numeral page numbering for prefaces and front matter
- Verify Roman numeral annotations on historical maps and manuscripts
- Teach or learn subtractive notation rules in a computer science or history class
Frequently Asked Questions
QWhy does IV mean 4 rather than IIII?
Subtractive notation allows a smaller symbol placed before a larger one to indicate subtraction. IV (5 − 1 = 4) is preferred over IIII because it reduces the number of symbols and eliminates ambiguous groupings. However, IIII still appears on some clock faces by historical convention.
QWhy is 4000 not representable in standard Roman numerals?
Standard Roman numerals use M for 1000, and repeating M more than three times (MMMM for 4000) is not permitted under classical rules. Extended notations using a vinculum (overline) exist for larger numbers but are non-standard.
QAre lowercase Roman numerals valid?
Yes. Lowercase roman numerals (i, v, x, l, c, d, m) are commonly used in legal documents, dissertations, and book front matter. This tool accepts both cases as input and can output either.
QWhat is the current year in Roman numerals?
The tool displays the current year automatically. For reference, 2024 = MMXXIV (2000 + 20 + 4), and 2025 = MMXXV.
QWhat makes a Roman numeral string invalid?
Common errors include using a symbol more than three times in succession (e.g., IIII), invalid subtractive pairs (e.g., IL or IC), or symbols out of descending order (e.g., XCX). The validator identifies the specific error.