Los números romanos siguen presentes en siglos, reyes, capítulos, olimpiadas y relojes, pero sus reglas no siempre se recuerdan. Aquí tienes la guía completa: símbolos, reglas de lectura, tabla de referencia, errores comunes y un conversor automático al final.
Los siete símbolos básicos
| Símbolo | Valor | Origen |
|---|---|---|
| I | 1 | dedo (unus) |
| V | 5 | mano abierta (quinque) |
| X | 10 | dos manos cruzadas (decem) |
| L | 50 | (quinquaginta) |
| C | 100 | centum |
| D | 500 | (quingenti) |
| M | 1000 | mille |
Con estos siete símbolos se escribe cualquier cifra del 1 al 3999 en notación clásica.
Las dos reglas de lectura
Regla 1 — Suma: si un símbolo va seguido de otro de igual o menor valor, se suman. Ej: VI = 6, LX = 60, MC = 1100. Regla 2 — Resta: si un símbolo va seguido de otro de mayor valor, se resta. Ej: IV = 4, XC = 90, CM = 900.
Solo hay seis restas válidas:
| Resta | Valor | Resta | Valor |
|---|---|---|---|
| IV | 4 | XL | 40 |
| IX | 9 | XC | 90 |
| CD | 400 | CM | 900 |
No se escribe por ejemplo IL para 49 ni IC para 99: lo correcto es XLIX y XCIX.
Tabla de referencia (1–1000)
| Valor | Romano | Valor | Romano | Valor | Romano |
|---|---|---|---|---|---|
| 1 | I | 10 | X | 100 | C |
| 2 | II | 20 | XX | 200 | CC |
| 3 | III | 30 | XXX | 300 | CCC |
| 4 | IV | 40 | XL | 400 | CD |
| 5 | V | 50 | L | 500 | D |
| 6 | VI | 60 | LX | 600 | DC |
| 7 | VII | 70 | LXX | 700 | DCC |
| 8 | VIII | 80 | LXXX | 800 | DCCC |
| 9 | IX | 90 | XC | 900 | CM |
| 10 | X | 100 | C | 1000 | M |
Fechas y años modernos
| Año | Romano |
|---|---|
| 1987 | MCMLXXXVII |
| 1999 | MCMXCIX |
| 2000 | MM |
| 2015 | MMXV |
| 2024 | MMXXIV |
| 2026 | MMXXVI |
Errores más comunes
- ❌ IIII para 4 → lo correcto es IV (el IIII solo aparece en relojes por tradición).
- ❌ VV para 10 → lo correcto es X; nunca se repite V, L ni D.
- ❌ IIIII para 5 → lo correcto es V; un mismo símbolo se repite como máximo 3 veces.
- ❌ IC para 99 → lo correcto es XCIX; solo se restan los pares de la tabla anterior.
Cómo convertir con nuestra herramienta
- Escribe un número decimal (del 1 al 3999) en el primer campo y el romano aparecerá al instante.
- O teclea un número romano en el segundo campo y verás su valor decimal.
- Despliega el desglose para ver cada símbolo y cuánto suma.
💡 Desglose de ejemplo: MCMLXXXVII = M + CM + LXXX + VII = 1000 + 900 + 80 + 7 = 1987.
Conclusión
- Siete símbolos y dos reglas (suma y resta) bastan para leer cualquier número romano.
- Máximo estándar: 3999 (
MMMCMXCIX). - Errores frecuentes: IIII y VV; usa IV y X.
- El desglose símbolo a símbolo es la mejor forma de entender cada cifra.
Roman numerals are still found in centuries, royal names, book chapters, the Olympic Games and some clocks, but their rules are not always remembered. Here is the complete guide: symbols, reading rules, reference table, common mistakes and an automatic converter at the end.
The seven basic symbols
| Symbol | Value | Origin |
|---|---|---|
| I | 1 | finger (unus) |
| V | 5 | open hand (quinque) |
| X | 10 | two crossed hands (decem) |
| L | 50 | (quinquaginta) |
| C | 100 | centum |
| D | 500 | (quingenti) |
| M | 1000 | mille |
With these seven symbols you can write any number from 1 to 3999 in classical notation.
The two reading rules
Rule 1 — Addition: when a symbol is followed by one of equal or lesser value, add them. Ex: VI = 6, LX = 60, MC = 1100. Rule 2 — Subtraction: when a symbol is followed by one of greater value, subtract. Ex: IV = 4, XC = 90, CM = 900.
Only six subtractions are valid:
| Subtraction | Value | Subtraction | Value |
|---|---|---|---|
| IV | 4 | XL | 40 |
| IX | 9 | XC | 90 |
| CD | 400 | CM | 900 |
For example, IL for 49 and IC for 99 are wrong; the correct forms are XLIX and XCIX.
Reference table (1–1000)
| Value | Roman | Value | Roman | Value | Roman |
|---|---|---|---|---|---|
| 1 | I | 10 | X | 100 | C |
| 2 | II | 20 | XX | 200 | CC |
| 3 | III | 30 | XXX | 300 | CCC |
| 4 | IV | 40 | XL | 400 | CD |
| 5 | V | 50 | L | 500 | D |
| 6 | VI | 60 | LX | 600 | DC |
| 7 | VII | 70 | LXX | 700 | DCC |
| 8 | VIII | 80 | LXXX | 800 | DCCC |
| 9 | IX | 90 | XC | 900 | CM |
| 10 | X | 100 | C | 1000 | M |
Modern years and dates
| Year | Roman |
|---|---|
| 1987 | MCMLXXXVII |
| 1999 | MCMXCIX |
| 2000 | MM |
| 2015 | MMXV |
| 2024 | MMXXIV |
| 2026 | MMXXVI |
Most common mistakes
- ❌ IIII for 4 → the correct form is IV (IIII only appears on clocks by tradition).
- ❌ VV for 10 → the correct form is X; V, L and D are never repeated.
- ❌ IIIII for 5 → the correct form is V; any symbol is repeated at most three times.
- ❌ IC for 99 → the correct form is XCIX; only the six pairs above are used for subtraction.
How to use the converter
- Enter a decimal number (from 1 to 3999) in the first field and the Roman numeral appears instantly.
- Or type a Roman numeral in the second field and you will see its decimal value.
- Expand the breakdown to see each symbol and its contribution.
💡 Breakdown example: MCMLXXXVII = M + CM + LXXX + VII = 1000 + 900 + 80 + 7 = 1987.
Conclusion
- Seven symbols and two rules (addition and subtraction) are enough to read any Roman numeral.
- Standard maximum: 3999 (
MMMCMXCIX). - Common errors: IIII and VV; use IV and X instead.
- The symbol-by-symbol breakdown is the best way to understand each figure.