ποΈ Roman Numeral Converter
Both directions, with validation of proper numeral form.
Converted
Roman Numeral Reference
| Symbol | Value | Symbol | Value |
|---|---|---|---|
| I | 1 | XC | 90 |
| V | 5 | C | 100 |
| X | 10 | CD | 400 |
| L | 50 | D | 500 |
| IV | 4 | CM | 900 |
| IX | 9 | M | 1000 |
| XL | 40 |
How to Use This Converter
Choose a direction, type the value, and get the instant conversion. Number-to-Roman handles 1 through 3999 (MMMCMXCIX). Roman-to-number validates the input and rejects malformed numerals like "IIII" or "VX," explaining proper form.
Pick Number to Roman or Roman to Number.
Type the number (1-3999) or the numeral (letters IVXLCDM).
Read the result. Invalid numerals show exactly what is wrong.
How Roman Numerals Work
Roman numerals are additive with subtractive shortcuts. Symbols are written largest to smallest and summed: XVI = 10 + 5 + 1 = 16. To avoid four repeats, a smaller symbol before a larger one subtracts: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900. Only these six subtractive pairs are legal; "IL" for 49 is wrong (use XLIX).
The rules: I, X, C, M repeat up to three times; V, L, D never repeat; subtractive pairs use only the six listed forms; symbols decrease left to right except for subtractive pairs. The largest standard numeral is MMMCMXCIX (3,999), since Romans had no zero and no standard form beyond M.
Where You Still See Them
Roman numerals survive in copyright years on films, Super Bowl numbers, clock faces (where IIII is traditional on clock faces despite being "wrong" elsewhere), monarch and pope names, and outlines in formal documents. Tattoo artists report them among the most requested designs, which makes validation genuinely useful before the ink.
Worked Example
Convert 2026: break into 2000 + 20 + 6. 2000 = MM, 20 = XX, 6 = VI, giving MMXXVI. Check: M(1000) + M(1000) + X(10) + X(10) + V(5) + I(1) = 2026. Reverse: MCMLXXXIV. M before CM? No: M = 1000, CM = 900, LXXX = 80, IV = 4, total 1984.
Validation Rules
This converter enforces classical form: no more than three repeats of I, X, C, M; no repeats of V, L, D; only the six legal subtractive pairs; and strictly decreasing values otherwise. "IIII" fails (use IV), "VX" fails (use V), and "IC" fails (use XCIX for 99). Real-world clock faces and old inscriptions sometimes break these rules, but modern standard form follows them.
Roman Numerals in Modern Design
Designers love Roman numerals for their classical weight: chapter headings, luxury brand marks, wedding invitations, and building cornerstones. A few style rules keep them looking right. Use uppercase for formal contexts and lowercase (iv, xii) for outlines and lists. Never mix cases in one document. For years on monuments, the full subtractive form is standard: 2024 is MMXXIV, not MMXXIIII. When in doubt, run the value through this converter and copy the validated result.
Frequently Asked Questions
What is 2026 in Roman numerals?
MMXXVI. Break it down: 2000 = MM, 20 = XX, 6 = VI. Combined: MMXXVI.
Why is 4 written as IV and not IIII?
Subtractive notation: a smaller numeral before a larger one subtracts. IV = 5 β 1 = 4. This avoids four repeats and is the standard form, though clock faces traditionally use IIII for symmetry.
What is the largest Roman numeral?
MMMCMXCIX = 3,999. The standard system has no symbols beyond M (1,000) and no zero, so larger numbers need non-standard extensions like overlines.
How do you read MCMLXXXIV?
1984. M = 1000, CM = 900, LXXX = 80, IV = 4. Add them: 1000 + 900 + 80 + 4 = 1984.
Is IIII ever correct?
In classical standard form, no (use IV). But clockmakers have used IIII for centuries, possibly for visual balance with VIII on the opposite side. Inscriptions and clocks often bend the rules.