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Roman Numeral Converter

Convert Arabic numbers and Roman numerals in either direction, including dates, lists, and vinculum notation up to 3,999,999.

Number or Roman Numeral

ExampleSample values — edit any field to see your result.

Results update as you type.

Result

LXIII = 63

Estimated result

Steps
LXIII = L + X + I + I + I = 63
ResultLXIII = 63
Convert Arabic numbers to Roman numerals or Roman numerals back to numbers. A second mode handles dates and multiple values while preserving their separator.

Formula

Symbols normally add from largest to smallest. A smaller valid symbol before a larger one subtracts: IV = 5 − 1, IX = 10 − 1, XL = 50 − 10, XC = 100 − 10, CD = 500 − 100, and CM = 1,000 − 100.

Examples

LXIII

L + X + I + I + I = 50 + 10 + 1 + 1 + 1 = 63.

2026/09/13

The date converts to MMXXVI/IX/XIII.

Vinculum

Enter _V for 5,000. The converter supports values through 3,999,999.
Roman numeral conventions varied historically. This converter enforces the common modern subtractive form so every number has one unambiguous representation.

Frequently asked questions

What Roman numeral symbols are used?
I, V, X, L, C, D, and M represent 1, 5, 10, 50, 100, 500, and 1,000.
How are numbers larger than 3,999 entered?
Put an underscore before a symbol to represent a vinculum, multiplying that symbol by 1,000. For example, _V represents 5,000.
Can I convert a date?
Yes. The date/list mode converts each component while preserving separators including slash, dash, period, backslash, vertical bar, or space.
Why is IIII rejected?
The converter uses canonical modern Roman notation, where 4 is IV and I, X, C, and M may repeat no more than three times consecutively.

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