Roman Numeral Converter – Number to Roman Numerals Online Free
The Roman Numeral Converter is a free online tool that instantly converts numbers to Roman numerals and Roman numerals back to numbers. It supports numbers from 1 to 3,999,999 (using vinculum/overline notation for values above 3,999), includes a batch converter for up to 100 values, quick-click examples, and a full reference table for symbols and subtractive notation. All conversion happens in your browser.
Frequently Asked Questions
How do I convert a number to Roman numerals?
Select the "Number → Roman" mode (selected by default), type your number in the input field, and the Roman numeral equivalent appears instantly below. Numbers from 1 to 3,999 use standard Roman notation (I, V, X, L, C, D, M). Numbers from 4,000 to 3,999,999 use vinculum notation with an overline bar (e.g. V̄ = 5,000).
How do I convert Roman numerals to a number?
Click the "Roman → Number" tab, type or paste your Roman numerals (uppercase or lowercase), and the decimal number appears instantly. The converter validates the input using a round-trip check — it converts to a number and then back to Roman numerals to verify the result is canonical.
What is the maximum number supported?
The converter supports numbers from 1 to 3,999,999. Numbers above 3,999 use vinculum notation (a bar over the symbol to multiply it by 1,000). For example, V̄ = 5,000, X̄ = 10,000, M̄ = 1,000,000. The reverse converter (Roman → Number) only supports standard notation up to 3,999.
What are subtractive Roman numerals?
Subtractive notation is a rule in Roman numerals where a smaller value placed before a larger one means subtraction. For example: IV = 4 (5−1), IX = 9 (10−1), XL = 40, XC = 90, CD = 400, CM = 900. This avoids writing IIII for 4 or VIIII for 9.
How does the batch converter work?
Click "Batch converter" to expand the panel. Enter one number per line (up to 100 numbers, each between 1 and 3,999). The results appear immediately on the right. You can copy all results to the clipboard or download them as a .txt file.
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