Calculators & Converters
Roman Numeral Converter
Convert a whole number into standard Roman numerals or translate a conventional Roman numeral back to a decimal number. The converter validates canonical notation from 1 to 3999.
Convert Roman numerals
Roman Numeral Converter
Convert standard Roman numerals in the conventional 1–3999 range.
Conversion
Result
Breakdown
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Roman numeral conversion is processed locally in your browser and is not transmitted or stored by this tool.
Roman numeral reference
| Numeral | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1000 |
| IV / IX | 4 / 9 |
| XL / XC | 40 / 90 |
| CD / CM | 400 / 900 |
Conversion and validation run in your browser. The values you enter are not sent to ToolHub.
How to use the Roman numeral converter
- 1
Choose number to Roman numeral or Roman numeral to number.
- 2
Enter a whole number from 1 to 3999, or a standard numeral from I to MMMCMXCIX.
- 3
Select Convert.
- 4
Review the result and its symbol-by-symbol breakdown.
- 5
Copy the validated result.
How Roman numeral conversion works
Roman notation combines I, V, X, L, C, D and M. Most symbols add value, while accepted subtractive pairs place a smaller symbol before a larger one: IV is 4, IX is 9, XL is 40, XC is 90, CD is 400 and CM is 900. Number-to-Roman conversion repeatedly takes the largest valid value. Roman-to-number conversion parses the symbols and then rebuilds the numeral to confirm that the input uses standard canonical form.
Roman numeral examples
2026 = MMXXVI. The breakdown is MM = 2000, XX = 20 and VI = 6. Another common example is 1994 = MCMXCIV, using CM, XC and IV.
Birthday and date Roman numerals
A Roman numeral converter can help check a year, birthday or date design. Convert each date part separately if the intended format contains a day, month and year. Roman numerals do not show which part is the month or day, so keep separators and the original date order clear. Verify permanent uses such as tattoos, engraving and jewellery with a second source and a human review.
Why some inputs are rejected
The tool accepts conventional modern notation. It rejects noncanonical forms such as IIII for 4, even though unusual forms sometimes appear on clocks or historical objects. It also rejects zero, negative values and numbers above 3999 because ordinary Roman notation has no single universal modern standard for them.
Important limitations
- Range: supported values are 1 through 3999.
- Standard form: alternative historical spellings are not accepted.
- Dates: conversion does not confirm that a calendar date is real.
- No overlines: extended notation for values above 3999 is not generated.
Related tools
Roman Numeral Converter FAQ
How do I convert Roman numerals to numbers?
Choose Roman numeral to number, enter a standard numeral such as MCMXCIV and select Convert.
What is 2026 in Roman numerals?
The standard Roman numeral for 2026 is MMXXVI.
Can I convert a birthday or date?
Yes. Convert each number separately and preserve clear day, month and year separators.
Why is IIII rejected?
This converter requires canonical modern notation, where 4 is written IV.
Can Roman numerals represent zero?
Ordinary Roman notation used by this tool has no zero.
What is the highest supported number?
The supported range ends at 3999, written MMMCMXCIX.
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