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About Roman Numerals Converter Online
This tool converts between Arabic numerals (1, 2, 3...) and Roman numerals (I, II, III...). It supports the standard range from 1 to 3,999, which covers virtually every practical use of Roman numerals today.
Roman numerals appear in regnal names (Henry VIII), Super Bowl numbers (Super Bowl LVIII), copyright dates on movie credits, book chapter numbers, watch faces, and outline numbering. The tool follows modern subtractive rules (IV for 4, IX for 9, etc.).
Use it to decode an unfamiliar Roman numeral, convert dates into stylish Roman format, name a sequel ("Volume IV"), or check a tattoo before getting inked.
How to use this tool
How to convert between Arabic and Roman numerals
Set the direction
"Direction" picks `toRoman` (number → numeral) or `toArabic` (numeral → number). Pick once per run; both sides accept the appropriate format.
Enter the value
"Value" is the number or numeral to convert. For `toRoman`, valid inputs are integers 1–3999 — beyond that, classical Roman numerals require overline notation which this tool doesn't emit. For `toArabic`, accepted letters are `I V X L C D M`; lowercase and uppercase both parse.
Press Run
Result returns a single `result` field — the converted form. Examples: `2026` → `MMXXVI`; `MCMLXXXIV` → `1984`. Subtractive notation is used (`IV` for 4, `IX` for 9, `XL` for 40, `CD` for 400, `CM` for 900) — never `IIII` or `VIIII`.
Where the limit comes from
Romans had no zero, no decimal places, and represented 5000+ with overlines on the same letters. This tool stops at 3999 (`MMMCMXCIX`) because anything higher needs that overline (or modern Unicode characters) and there's no canonical ASCII rendering.