Convert numbers to Roman numerals and translate Roman numerals back to decimal free online. Covers 1 to 3,999 with step-by-step breakdowns — no signup.
This Roman numeral converter online free translates any integer between 1 and 3,999 to Roman numeral notation and back again instantly. Type a decimal number to get the Roman equivalent, or enter Roman symbols to get the decimal value — with a step-by-step breakdown showing exactly how the conversion was made. As a number to Roman numeral translator, it correctly applies the subtractive notation rules that make Roman numerals work: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900. Each conversion is broken down symbol by symbol so you can follow the logic clearly. Want to know how to write 2025 in Roman numerals for a design project? Need a tattoo Roman numeral date converter to check your date before it becomes permanent? Want to understand Roman numeral clock faces? This tool handles all of these clearly and instantly. Free, no account required.
The Roman Numeral Converter translates any integer between 1 and 3,999 to Roman numeral notation and converts Roman numerals back to standard integers. Roman numerals use seven letters: I (1), V (5), X (10), L (50), C (100), D (500), and M (1000). Values are written largest to smallest from left to right; a smaller value placed before a larger one is subtracted (subtractive notation). For example, IV = 4 (5−1), IX = 9 (10−1), XL = 40, XC = 90, CD = 400, CM = 900. The tool validates your input and highlights invalid numeral sequences in real time, so you can learn the rules as you convert.
Formula
Value = sum of all numeral values, where a numeral preceding a larger numeral is subtracted rather than added. IV = V − I = 4, IX = X − I = 9, XL = L − X = 40, XC = C − X = 90, CD = D − C = 400, CM = M − C = 900.
| Roman | Decimal | Roman | Decimal |
|---|---|---|---|
| I | 1 | L | 50 |
| II | 2 | LX | 60 |
| III | 3 | LXX | 70 |
| IV | 4 | LXXX | 80 |
| V | 5 | XC | 90 |
| VI | 6 | C | 100 |
| VII | 7 | D | 500 |
| VIII | 8 | M | 1,000 |
| IX | 9 | MM | 2,000 |
| X | 10 | MMM | 3,000 |
| XX | 20 | MMMCMXCIX | 3,999 |
| XL | 40 | MMXXVI | 2,026 |
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