Roman Numeral Converter
Enter an Arabic number (1–3999) or a standard Roman numeral (I, V, X, L, C, D, M) to get the other form and a breakdown of each symbol's value. Common uses include Super Bowl numbering, movie copyright dates, book chapter titles, clock faces, monuments and tattoos.
Enter a whole number from 1 to 3999.
Roman numeral
MMXXIV
Arabic number
2024
Breakdown
How the result decomposes into individual Roman symbols.
| Symbol | Value |
|---|---|
| MM | 2000 |
| XX | 20 |
| IV | 4 |
Supported range: 1–3999. Uses standard subtractive notation (IV = 4, IX = 9, XL = 40 …) and rejects non-standard forms like IIII, VV or IC. Zero and negatives have no historical Roman symbol.
Formula
Seven base symbols: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000 Subtractive pairs: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900 Greedy expansion: at each step take the largest base symbol or subtractive pair that still fits; I, X, C, M may repeat up to 3 times; V, L, D never repeat.
- · Supported range: 1–3999. Ancient Rome had no symbol for zero or negatives; 4000 is traditionally written as IV with an overline (×1000), which is not supported in plain text.
- · Only standard subtractive notation is accepted. Non-standard forms like IIII (still seen on clock faces), VV, IC or XCXC are rejected.
- · Romans themselves did not consistently use standard subtractive notation — IIII persisted on clock faces into the modern era; the strict standard form was popularised from the 19th century onward.
- · Common uses: movie copyright dates (MMXX = 2020), Super Bowl numbering (LIX = 59), British monarchs (Elizabeth II), popes (Pope John XXIII), older chemistry group labels (IA, VIIA).
- · Conversion uses a greedy algorithm: at each step take the largest base symbol or subtractive pair that fits; for any integer in 1–3999 the standard form is unique.
- · Sources: Encyclopedia Britannica "Roman numeral"; The Chicago Manual of Style. Tests cover the full 1–3999 round trip for toRoman / fromRoman.
Frequently asked
Why don't you support 0, 4000 or negative numbers?
Ancient Roman numerals had no symbol for zero (the concept entered Europe later via Indian mathematics) and no notation for negatives. Numbers ≥ 4000 historically used an overline to multiply by 1000 (e.g. V̄ = 5000), but that does not render reliably in plain text, so this tool sticks to 1–3999 — enough for book chapters, sports event numbering and almost every year you'll meet in practice.
Which is correct — IIII or IV?
Strictly speaking IV is the modern standard. But IIII is still extremely common on clock faces (especially mechanical watches) for visual symmetry — VIII and IIII both have four characters. This tool follows the standard, so IIII is rejected, and entering 4 produces IV.
How do I read MMXXIV or MCMLXXXIV?
Read left to right and group: MMXXIV = MM (1000+1000) + XX (10+10) + IV (5−1) = 2024. MCMLXXXIV = M (1000) + CM (1000−100) + LXXX (50+10+10+10) + IV (5−1) = 1984. The breakdown table below shows the value of each Roman symbol so you can check at a glance.
Can I do arithmetic in Roman numerals?
This tool only handles notation conversion, not arithmetic — positional Arabic numerals are far better for sums and products. The practical workflow: convert your Roman numerals to Arabic here, do the math in any calculator, then convert the result back.
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