Roman Numeral Converter
Convert numbers to Roman numerals and back — free, no signup, live as you type, with steps shown.
Roman numerals have no zero and no standard form above 3999, so this converter covers 1–3999 only. Dates are shown day, month and year, each converted separately.
What Is the Roman Numeral Converter?
A roman numeral converter is a tool that turns an ordinary number into Roman numerals — the letter system used by ancient Rome (I, V, X, L, C, D, M) — and turns Roman numerals back into an ordinary number. Type 1984 and it shows MCMLXXXIV with the steps; type MCMLXXXIV and it shows 1984, so you can check homework, clock faces, book chapters and film credits in either direction.
What Is It Used For?
Students use it for maths homework and history assignments involving Roman numerals. Readers use it to decode chapter numbers, book volumes and film copyright years. Tattoo and design fans use it to check a year before making it permanent. Teachers use the step breakdown to show how the subtractive system (IV for 4, IX for 9) actually works.
Key Benefits
- Both directions, live — number to Roman and Roman to number, updating as you type in either box.
- Step-by-step breakdown — every conversion shows how the answer is built, piece by piece.
- Date mode — pick any calendar date and see the day, month and year in Roman numerals.
- Real validation — out-of-range numbers and non-standard Roman forms get a clear error, not a wrong answer.
- Completely free and private — no signup, and everything runs in your browser.
How to Use This Roman Numeral Converter
- Type a whole number from 1 to 3999 in the Number box — the Roman numeral and its steps appear below instantly.
- Or type a Roman numeral in the Roman box — the number and its steps appear instead.
- For a date, pick it in the Date mode picker — the day, month and year are each converted and shown together.
- Click Copy Result to copy the converted value.
Common Mistakes to Avoid With Roman Numerals
- Writing IIII instead of IV. Roman numerals use subtraction: 4 is IV (one before five), not IIII, and 9 is IX, not VIIII.
- Repeating a symbol too many times. I, X, C and M may repeat at most three times in a row; V, L and D are never repeated.
- Putting a smaller value before a larger one that does not allow it. Only I, X and C subtract, and only from the next two larger values (I before V or X, X before L or C, C before D or M) — IL for 49 is wrong; it is XLIX.
- Expecting a zero. Roman numerals have no symbol for zero, so 0 and negative numbers cannot be converted.
- Going above 3999. The standard system tops out at 3999 (MMMCMXCIX). Larger numbers need a bar over letters, which this converter does not support.
Frequently Asked Questions
Is this Roman numeral converter free? Yes, completely free — no signup, no download, no limits.
Is anything I type uploaded anywhere? No. Conversion happens entirely in your browser, so nothing you type leaves your device.
What range does it cover? Whole numbers from 1 to 3999. Roman numerals have no zero and no standard form above 3999, so numbers outside that range show a clear error instead of a made-up answer.
How does the step breakdown work? The number is split into thousands, hundreds, tens and ones, and each part is converted separately — for example 1984 becomes M (1000) + CM (900) + LXXX (80) + IV (4) = MCMLXXXIV.
Why is 4 written as IV and not IIII? Because of the subtractive rule: a smaller symbol before a larger one is subtracted. IV means 5 − 1 = 4, and IX means 10 − 1 = 9. Clock faces sometimes show IIII for 4 by tradition, but that is the exception, not the rule.
What is the largest Roman numeral? In this standard system, 3999, written MMMCMXCIX. Larger values historically used a bar over a letter to mean times 1,000, which this tool does not support.
Does it accept lowercase Roman numerals? Yes. Lowercase input such as "xiv" is read as XIV and converts to 14.
Why does it reject some Roman numerals? Because they are not in standard form — for example IIII, VV, IL or VX break the repetition or subtraction rules. The tool rejects them with an error rather than guessing a number.
How does date mode work? Pick a calendar date and the tool converts the day, month and year separately — for example, 31 October 2026 becomes XXXI · X · MMXXVI. It shows the date as day, month, year, in that order.
Can I convert a year only? Yes. Type the year (for example 2026) in the Number box and it converts to MMXXVI — you do not need the date picker for a year alone.
What are the seven symbols? I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000. Every Roman numeral is built from these seven letters.
Does it work on mobile? Yes. The tool runs in any modern mobile browser and the layout adjusts to small screens.
Can I copy the result? Yes — Copy Result copies the converted value (the Roman numeral or the number) for pasting elsewhere.
Final Thoughts
Roman numerals look simple until subtraction and the 3999 limit show up — this converter handles both, with steps, so you learn the system instead of just copying an answer. Bookmark it for homework, chapters and years.