🏛️ Roman Numeral & Number Base Converter

Convert any number to Roman numerals (with overline notation for 4,000+), binary, octal, hexadecimal, base-36, words, ordinal and scientific form — or type a Roman numeral, binary or hex value and read it back as decimal. Includes a quick year table.

Enter a number, Roman numeral, 0b…, 0o…, 0x…

Roman numeral

MMXXVI

Roman numeral cheat-sheet & rules

I
1

V
5

X
10

L
50

C
100

D
500

M
1000

V
5000

Symbols are added left to right (VI = 6) unless a smaller value precedes a larger one, in which case it's subtracted (IV = 4).
Only I, X and C can be subtracted, and only from the next two higher symbols (IV, IX, XL, XC, CD, CM).
No symbol repeats more than three times in a row — 4 is IV, not IIII (clock faces are the famous exception).
A bar over a numeral multiplies it by 1,000 (V̅ = 5,000). Romans had no zero; "nulla" was used in medieval texts.

Common years: 1066 = MLXVI · 1776 = MDCCLXXVI · 1999 = MCMXCIX · 2000 = MM · 2024 = MMXXIV · 2026 = MMXXVI