Roman Numeral Converter
Numbers to Roman numerals and back, with the rules that make one valid.
Last updated
Your details
Type either a number from 1 to 3999, or a Roman numeral.
Result
- 2,026 in Roman numerals
- MMXXVI
- Read as
- M · M · X · X · V · I
- Letters used
- 6
Formula — written step by step
Writing 2026…
Largest value that fits, subtract, repeat
2026 − 1000 = 1026 → M
1026 − 1000 = 26 → MM
26 − 10 − 10 = 6 → MMXX
6 − 5 − 1 = 0 → MMXXVI
MMXXVI
The seven letters are I, V, X, L, C, D and M — one, five, ten, fifty, a hundred, five hundred and a thousand. Values are written largest first and added, except for the six subtractive pairs.
A worked example
Why 1994 is MCMXCIV
- Number
- 1994
- 1000 → M
- 900 → CM (a hundred before a thousand)
- 90 → XC (ten before a hundred)
- 4 → IV (one before five)
MCMXCIV
Four subtractive pairs in one numeral. Writing 1994 as MDCCCCLXXXXIIII would still add up, but it is not valid form.
How to use this calculator
- Type either a number from 1 to 3999, or a Roman numeral — the converter works out which you meant.
- Numerals are checked for validity, not just added up: IIII and IC are rejected because neither is canonical form.
- There is no zero and no negative number in the system, which is part of why it was eventually replaced for arithmetic.
The subtractive rule, and its six legal pairs
Placing a smaller value before a larger one means subtract rather than add: IV is four, not six. Only six pairs are permitted — IV, IX, XL, XC, CD and CM — and each subtracts a power of ten from the next one or two steps up.
That restriction is why IC is invalid for 99. The correct form is XCIX: ninety written as XC, then nine as IX.
Where the system stops
Classical Roman numerals run out at 3,999. Larger numbers needed a vinculum — an overline multiplying a numeral by a thousand — which plain text cannot render reliably, so this converter stops at MMMCMXCIX.
They persist where a number is decorative or ordinal rather than arithmetic: clock faces, book chapters, film sequels, monarchs and the Super Bowl. Nobody does long division in them, which is the point.
Frequently asked questions
Why is there no zero in Roman numerals?
The system counts things rather than holding place values, so there was nothing for a zero to do. Positional notation, which needs a zero to distinguish 105 from 15, arrived in Europe much later with Arabic numerals.
Is IIII ever correct?
Not in standard form, though clock faces often use it for IV — partly for visual balance against the VIII opposite. This converter follows the standard and rejects it.
How do I write my birth year?
Type it in and read the result. Years beginning with 19 start MCM, and years beginning with 20 start MM.