What numbers can be converted to Roman numerals?

The standard Roman numeral system covers integers from 1 to 3,999 (MMMCMXCIX). Numbers outside this range cannot be represented using the classical rules. This tool supports the full 1 to 3,999 range.

What are the subtractive rules in Roman numerals?

Roman numerals use subtractive notation for six combinations: IV (4), IX (9), XL (40), XC (90), CD (400), and CM (900). A smaller value placed before a larger one means the smaller is subtracted. All other symbols are additive.

Is this tool completely free?

Yes. The tool is completely free to use with no registration, no account, and no payment required.

Is my data sent to a server?

All conversions run locally in JavaScript in your browser. No data is sent to our servers.

Roman numeral converter

Roman numeral converter is a math tool that translates between Arabic numbers and Roman numerals. It supports the standard range 1 to 3,999, handles subtractive notation (IV, IX, XL, XC, CD, CM), and shows a reference table of all symbols. The tool runs in your browser.

Enter a number (1–3,999)

Dedicated pages

Direction-specific Roman numeral converters.

Roman numeral to number converter

Convert Roman numerals to regular numbers instantly. Supports I to MMMCMXCIX (1–3,999). Free, runs in your browser.

Number to Roman numeral converter

Convert any number (1–3,999) to Roman numerals instantly. Type the number and see the Roman numeral in real time. Free, in-browser.

Roman numeral chart and converter

Full Roman numeral chart (1–3,999) with an interactive converter. Convert numbers to Roman numerals and back. Free, in-browser.

How to use the Roman numeral converter

Choose a direction: number to Roman numeral, or Roman numeral to number.
Enter a number between 1 and 3999, or a valid Roman numeral.
The result appears instantly as you type.
Toggle the reference table to see the Roman numeral symbols and their values.

Common uses

Reading clock faces: analog clocks often use Roman numerals for their hour markers
Movie titles and dates: films and events frequently use Roman numerals for release years and sequel numbering
Related tools: fraction calculator and number base converter

Technical specification

Algorithm or formula: Greedy decimal-to-Roman conversion using the symbol-value pairs M (1000), CM (900), D (500), CD (400), C (100), XC (90), L (50), XL (40), X (10), IX (9), V (5), IV (4), I (1). Roman-to-decimal scans left to right, subtracting when a smaller value precedes a larger.
Browser API or library: Pure JavaScript; no external library.
Input limits: Integers 1 to 3,999 (the classical Roman range). Roman input must use uppercase I, V, X, L, C, D, M.
Output: Roman numeral string or decimal integer, with validation messages for out-of-range or malformed input.
Known limitations: Numbers above 3,999 (which historically used overbars to indicate multiplication by 1,000) are not supported. Zero and negative numbers have no Roman representation.

Frequently asked questions

What numbers can be converted to Roman numerals?: The standard Roman numeral system covers integers from 1 to 3,999 (MMMCMXCIX). Numbers outside this range cannot be represented using the classical rules. This tool supports the full 1 to 3,999 range.
What are the subtractive rules in Roman numerals?: Roman numerals use subtractive notation for six combinations: IV (4), IX (9), XL (40), XC (90), CD (400), and CM (900). A smaller value placed before a larger one means the smaller is subtracted. All other symbols are additive.
Is this tool completely free?: Yes. The tool is completely free to use with no registration, no account, and no payment required.
Is my data sent to a server?: All conversions run locally in JavaScript in your browser. No data is sent to our servers.

Reviewed and tested May 26, 2026.