Roman numeral converter for numbers, years and dates

Because the modern rule stops any letter from appearing four times in a row, so the fourth I is replaced by putting a single I in front of V. The Romans themselves were far less tidy about it: IIII is common on Roman inscriptions, and the same building often carried both forms — the numbered entrance arches of the Colosseum include additive spellings such as LIIII rather than LIV. The strict subtractive rule is a medieval and early-modern tidy-up that hardened once printers and schoolbooks settled on one version, which is why IIII is readable but only IV is standard.

No, there is no symbol for zero anywhere in the system, and there never was one. Roman numerals name quantities instead of filling positions, so unlike 205 in our own notation, no letter has to sit in a column to keep it empty. Where medieval writers genuinely needed a zero — in the Easter tables used to calculate the date of the feast — they wrote the Latin word nulla, or just the letter N. The digit 0 reached Western Europe with Hindu-Arabic numerals, carried into general use by Fibonacci's Liber Abaci in 1202.

2026 is MMXXVI. It is built place by place, exactly like any other number: MM is 2,000, XX is 20, and VI is 6. The neighbouring years follow the same pattern — 2024 is MMXXIV, 2025 is MMXXV and 2027 is MMXXVII — because a year carries no special rule of its own; it is simply a number that happens to be a date.

Mostly because IIII balances the dial and, on old clocks, made the numerals cheaper to cast. A dial that uses IIII needs exactly 20 I, 4 V and 4 X, which is four identical castings of five I, one V and one X; switch to IV and you need 17 I and 5 V, which no longer divides evenly. IIII also carries the same visual weight as the VIII sitting opposite it, so the face looks symmetrical. Big Ben is the well-known exception and uses IV.

3,999, written MMMCMXCIX, if you stay with the seven plain letters. M is the largest letter there is and no letter may repeat more than three times, so the plain system simply runs out. Larger numbers use a bar over the letters — the vinculum — which multiplies each one by 1,000, making V with a bar 5,000 and M with a bar 1,000,000. That takes the ceiling to 3,999,999, which is where this converter stops.

Because a letter may only be subtracted from the next two letters above it, and I only reaches as far as V and X. So 99 has to be assembled from 90 plus 9, which is XC followed by IX. The same rule blocks IL for 49 (it is XLIX), IM for 999 (it is CMXCIX) and XD for 490 (it is CDXC). Only I, X and C are ever subtracted at all; V, L and D never are.

Convert each part on its own and set them side by side: VII · VIII · MMXXVI. Roman numerals have no separator of their own, so the dots, spaces, dashes or slashes between the parts are a modern choice and none of them is more correct than the others. There are no leading zeros either, so the 07 in 07.08.2026 is simply VII. The one thing worth settling before it goes on a wall or a wrist is the order: III · IV · MMXX reads as 3 April to most of the world and as 4 March in the United States.