Roman Numeral Converter
Chuyển số ↔ số La Mã (1–3999)
Roman Numeral Converter
This free Roman numeral converter lets you translate any integer between 1 and 3999 into classical Roman notation — for example, 2024 becomes MMXXIV — or decode a Roman numeral string back to its decimal value in a single click. No installation, no account, and no limit on how many conversions you run: just type and get your answer instantly. Whether you need to label chapters, design a logo, or verify a date engraved in stone, this tool handles it accurately every time.
Benefits
Using a dedicated Roman numeral converter beats looking up a chart or calculating by hand in every situation:
- Instant results: Output appears as you type, with zero waiting or page reloads.
- Bidirectional: Convert integers to Roman numerals and Roman numerals to integers from the same interface.
- Validation built in: The tool flags invalid input — such as out-of-range numbers or malformed Roman strings — so you never get a silently wrong answer.
- Completely free: No subscription, no sign-up, and no usage cap.
- Works offline-ready: Runs entirely in your browser; no data is sent to a server.
Use cases
Roman numerals appear far more often than most people expect:
- Numbering chapters, sections, or acts in books, theses, screenplays, and legal documents (Chapter XI, Act III).
- Designing clocks, watch faces, trophies, gravestones, coats of arms, or any graphic that calls for classical style.
- Naming recurring events and sequels by year: Super Bowl LVIII, World Cup MMXXVI, Rocky IV.
- Developers formatting ordered lists or decorative counters in HTML and CSS using Roman numeral notation.
- Students and teachers checking homework or building quizzes on numeral systems.
- Historians and researchers decoding dates on coins, monuments, and archival documents.
How to use
Converting takes only a few seconds:
- Select the conversion direction: Number to Roman or Roman to Number.
- Type your value — an integer like 1776 or a Roman string like MDCCLXXVI.
- The result appears immediately beneath the input field.
- Click the copy button to grab the output and paste it wherever you need it.
- Clear the field and enter a new value to run another conversion.
Frequently asked questions
Why does the converter only go up to 3999? Standard Roman numerals top out at MMMCMXCIX (3999) because the system has no symbol for 4000 or higher; values beyond that require non-classical extensions not recognized in everyday use.
Does it matter whether I type uppercase or lowercase? No — the converter normalizes your input automatically, so mcmxcix and MCMXCIX both produce 1999 without any extra steps.
How does the tool know if a Roman numeral string is valid? It enforces standard subtractive notation rules — for instance, a symbol may not repeat more than three times consecutively, and VV or IIII will trigger a clear error message rather than returning a wrong number.
Can I convert a number with commas or decimal points? Please enter plain integers only (e.g., 1000, not 1,000 or 1000.0); the tool processes whole numbers in the range 1–3999 and will prompt you if the input format is not recognized.