Roman Numerals Calculator
Convert between Arabic and Roman numerals (1-3,999,999 with Vinculum). Customize mode adds arithmetic (+ − × ÷) between two Roman numerals and a reference chart.
Breakdown
- M1,000
- M1,000
- X10
- X10
- V5
- I1
Related tools
How to use
- 1
Arabic → Roman: enter any integer from 1 to 3,999,999.
- 2
Roman → Arabic: type the numeral using I, V, X, L, C, D, M.
- 3
Customize Arithmetic mode: enter two Roman numerals + an operation, get the answer in both Roman and Arabic.
- 4
Standard subtractive notation: 4 = IV (not IIII), 9 = IX, 40 = XL, 90 = XC, 400 = CD, 900 = CM.
Frequently asked questions
Romans didn't conceptualise zero as a number — it was treated as the absence of a value. Place-value notation (and zero) came from India via Arab mathematicians and reached Europe around the 12th century. By then Roman numerals were already entrenched for ceremonial uses, where they remained even after Arabic numerals took over for actual arithmetic.
MMMCMXCIX = 3,999. The single letters cap at M = 1,000. There's no standard single character for 5,000 or 10,000. Beyond 3,999 the Romans used Vinculum (a bar over a letter to multiply by 1,000) — so V̄ = 5,000, X̄ = 10,000, M̄ = 1,000,000. The calculator renders these with HTML overline.
Tradition more than rule. IV is mathematically correct (subtractive notation) but IIII is visually balanced against VIII on the opposite side of the dial. Big Ben uses IV; most other large clock faces use IIII. Both are accepted.
MMXXVI. Break it down: MM (2000) + XX (20) + VI (6) = 2026. The year 2024 was MMXXIV, 2025 is MMXXV.
Romans did arithmetic on a counting board (abacus), not symbolically with the numerals. The Customize Arithmetic mode converts each numeral to Arabic, does the operation, then converts back. Division is integer-only because Roman numerals can't represent fractions or decimals.
Watch faces, book chapters and prefaces, monarchs and popes, Olympic Games (Paris 2024 = XXXIII Olympiad), Super Bowls (Super Bowl LVII), copyright dates in old film credits, and outline numbering in formal documents (I, II, III, IV).
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Source: Standard subtractive Roman numeral convention; Vinculum per medieval / classical sources · Last verified 2026-06. This tool provides estimates only and is not legal, tax or financial advice. Always verify your specific situation with the relevant UAE authority or a licensed advisor before taking action.