Roman numeral converter — both directions
Read a Roman numeral as a number, or write a whole number from 1 to 3,999 in Roman numerals.
Runs in your browser — your input is not uploaded to ToolsNow.
Symbol values
Roman numerals have no zero and no standard way to write above 3,999 without overbars, which is why the range stops there. Invalid forms such as IIII and IC are rejected rather than silently accepted.
How to use
- Choose the direction. Select Number → Roman or Roman → Number.
- Enter the value. For example, 2026 becomes MMXXVI. In the reverse direction, lowercase mmxxvi works too.
- Use the symbol table to check it. M is 1,000, X is 10, V is 5 and I is 1, so MMXXVI is 2,000 + 20 + 5 + 1.
Questions
How does subtraction work?
The supported subtractive pairs are IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900). For example, 99 is XCIX: 90 + 9, not IC.
Why does a clock show IIII when this tool uses IV?
Some clocks use IIII. This converter follows the standard subtractive spelling and rejects alternatives such as IIII, so it is not a validator for every historical inscription or clock face.
What about zero or numbers above 3,999?
This tool supports only 1–3,999, using the seven letters in the table. It does not handle zero, fractions or extended forms such as overbar notation.
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