Ⅻ Decimal to Roman Numerals
Convert decimal numbers to Roman numerals and vice versa. Supports 1 to 3999.
About the Decimal ↔ Roman Converter
This converter runs entirely in your browser. Convert decimal numbers (1 to 3999) to Roman numerals, or parse a Roman numeral back to its decimal value. Nothing is uploaded — conversion happens locally with JavaScript.
Roman numeral symbols
I = 1,V = 5,X = 10,L = 50C = 100,D = 500,M = 1000- Subtractive forms:
IV = 4,IX = 9,XL = 40,XC = 90,CD = 400,CM = 900
Common use cases
- Numbering book chapters, movie sequels, or monarchy ordinals.
- Reading clock faces, building cornerstones, or page numbering in prefaces.
- Homework and classroom exercises on ancient numeral systems.
- Quick verification of a Roman numeral you encountered in a document.
Frequently asked questions
Why is the maximum 3999? Standard Roman numerals don't have a symbol for 5000 or above without using a vinculum (overline), which this tool doesn't support.
Does this tool upload my input? No. All conversion happens locally in your browser.
Is case sensitive? No. Roman numerals may be entered in upper or lower case; output is always uppercase.
Are invalid inputs handled? Yes. Invalid Roman numerals or out-of-range numbers show an error message in place of a result.