Roman Numeral Converter
The Roman Numeral Converter translates ordinary numbers into Roman numerals and Roman numerals back into numbers, live as you type. It covers 1 through 3999 — handy for dates, clock faces, movie copyright years, outlines, tattoos, and homework. Roman numerals avoid stacking more than three identical symbols in a row by using subtractive pairs: a smaller symbol placed before a larger one is subtracted instead of added, so IV reads as 5 − 1 = 4 and IX as 10 − 1 = 9. The standard system allows exactly six such pairs — IV, IX, XL, XC, CD, and CM — and this converter's algorithm checks for them largest-value-first before falling back to plain addition, which is also how it validates a typed Roman numeral as well-formed.
Converts both ways between ordinary numbers and Roman numerals (I to MMMCMXCIX, i.e. 1–3999). Type in either box and the other updates instantly. Everything runs in your browser.
How This Tool Works
Type a number (1–3999) to see its Roman numeral, or type a Roman numeral to see the number. Both fields stay in sync and each has a one-click copy button.
Formula & Method
Roman numerals combine the symbols I (1), V (5), X (10), L (50), C (100), D (500), and M (1000). Values are built largest-first, with subtractive pairs like IV (4) and IX (9) used where a smaller symbol precedes a larger one.
Example Calculation
Enter 1994 in the Number field: the algorithm takes the largest value that still fits at each step — 1000 (M) leaves 994, 900 (CM) leaves 94, 90 (XC) leaves 4, and 4 (IV) leaves 0 — producing MCMXCIV. Typing MCMXCIV into the Roman field reverses this by scanning left to right and subtracting a symbol's value whenever a smaller symbol precedes a larger one (the C before the second M, the X before the C), giving back 1994.
Frequently Asked Questions
What range does it support?+
Standard Roman numerals cover 1 to 3999 (MMMCMXCIX). Numbers outside that range can’t be written with the classic seven symbols.
How do I write a year like 2026 in Roman numerals?+
Type 2026 into the Number field and you’ll get MMXXVI. It works for any year from 1 to 3999.
Is zero a Roman numeral?+
No — the Roman system has no symbol for zero, so the converter starts at 1.
Why won't it accept IIII for 4?+
This converter follows the standard modern subtractive system, which caps any repeated symbol at three in a row (III, not IIII) and requires the subtractive pair IV instead. Older or clock-face styles that repeat symbols four times aren't accepted here.
Why does the range stop at 3999?+
3999 (MMMCMXCIX) is the ceiling because the standard system caps thousands at three M's, with no single symbol for 5,000 or higher. Historically a bar (vinculum) drawn over a numeral multiplied its value by 1,000 to go beyond that, but this converter doesn't support that extended notation.
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<a href="https://everyfix.net/tools/roman-numeral-converter/">Roman Numeral Converter</a> by <a href="https://everyfix.net">EveryFix</a>Related Tools
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