Roman numeral converter
2026 is MMXXVI — two M for a thousand each, XX for twenty, VI for six. Only I, X and C subtract, and only from the next two letters up, which gives exactly 6 subtractive pairs and is why 99 is XCIX rather than IC.
Numbers to numerals and numerals back to numbers, with every letter broken out. Type a numeral that is nearly right — IIII, VV, IC, MCMLXXXXIX — and it will read it anyway, then say which rule it breaks and how the number is actually written.
Round-tripped by test against every number to 3,999 · How we check
MCMXCIV
M = 1,000CM = 900 (subtracted)XC = 90 (subtracted)IV = 4 (subtracted)
1,994
Correctly written — this is how the convention spells 1,994.
M = 1000CM = 900XC = 90IV = 4
The seven letters
- I
- 1
- V
- 5
- X
- 10
- L
- 50
- C
- 100
- D
- 500
- M
- 1,000
Letters are added left to right, largest first, except in the six places where a smaller letter sits in front of a larger one and is subtracted instead: IV, IX, XL, XC, CD, CM. Those six are the whole of the subtractive rule. Anything else — IL, IC, XD — is not a numeral, however sensible it looks.
Years people look up
- 1776
- MDCCLXXVI
- 1969
- MCMLXIX
- 1994
- MCMXCIV
- 2000
- MM
- 2026
- MMXXVI
Questions people actually ask
- Why do clock faces use IIII instead of IV?
- Because it looks better, not because it is correct. A clock with IIII balances VIII across the dial, and casting a set of numerals for a clock face needs fewer moulds that way. The convention is genuinely old and genuinely wrong: 4 is IV, and every other context writes it that way.
- Why is 99 not IC?
- Because only I, X and C subtract, and only from the next two letters up: I from V and X, X from L and C, C from D and M. That gives exactly six subtractive pairs and IC is not one of them. 99 is XCIX — ninety, then nine — which looks longer and is the only conventional spelling.
- What is the largest Roman numeral?
- With the plain letters, 3,999 — MMMCMXCIX. There is no letter for five thousand, so four M in a row would be needed for 4,000 and that breaks the three-repeat rule. Above it the convention adds an overline meaning times a thousand, so a barred IV is 4,000 and the practical ceiling becomes 3,999,999.
- Is there a zero?
- No, and there is no need for one: the system is additive, so a place with nothing in it simply has no letter. Roman arithmetic managed without a zero for centuries. The word nulla was used for the absence of a quantity in medieval tables, but it is not a numeral and never appears inside one.
- Why do numerals repeat at most three times?
- Because the fourth is written by subtracting instead: IIII becomes IV, XXXX becomes XL, CCCC becomes CD. The rule applies only to I, X, C and M — the powers of ten. V, L and D never repeat at all, because two of them would just be the next letter up: VV is X.