Roman Numeral Converter
Roman Numeral Reference
Subtractive Notation
Common Years
Related Calculators
Understanding Roman Numerals
Basic Symbols
Roman numerals use seven basic symbols to represent numbers. These symbols can be combined to form any number from 1 to 3,999 using standard notation.
| Symbol | Value | Origin |
|---|---|---|
| I | 1 | Single tally mark |
| V | 5 | Hand (5 fingers) |
| X | 10 | Two hands crossed |
| L | 50 | Half of C (Ↄ) |
| C | 100 | Centum (Latin for 100) |
| D | 500 | Half of M (IↃ) |
| M | 1000 | Mille (Latin for 1000) |
Subtractive Notation
When a smaller value appears before a larger value, it's subtracted rather than added. This creates shorter representations for numbers like 4, 9, 40, 90, 400, and 900.
Rules for Roman Numerals
Rule 1: Symbols repeat up to 3 times
I, X, C, M can repeat up to 3 times (III=3, XXX=30). V, L, D never repeat.
Rule 2: Addition (larger before smaller)
When a larger value comes before a smaller, add them: VI = 5+1 = 6
Rule 3: Subtraction (smaller before larger)
When a smaller value comes before larger, subtract: IV = 5-1 = 4
Rule 4: Subtraction limits
I can precede V and X only. X can precede L and C only. C can precede D and M only.
Numbers 1-20
Modern Uses of Roman Numerals
Common Applications
- Super Bowl numbers (Super Bowl LVIII)
- Movie sequels (Rocky IV)
- Monarchs and popes (Queen Elizabeth II)
- Outlines and lists (I, II, III...)
- Clock faces (traditional watches)
- Copyright years (MMXXIV)
Historical Context
- Developed in ancient Rome
- Used throughout Roman Empire
- Replaced by Arabic numerals ~14th century
- Arabic numerals were more efficient for math
- Roman numerals lack zero concept
Limitations
Standard Roman numerals can only represent numbers from 1 to 3,999. There's no symbol for zero, and representing larger numbers requires additional notation (like a bar over symbols to multiply by 1,000).
Frequently Asked Questions
How do I convert a year to Roman numerals?
Break the number into thousands, hundreds, tens, and ones, then convert each part. For 2024: 2000=MM, 20=XX, 4=IV, giving MMXXIV. Use M for 1000s, C/D for 100s, X/L for 10s, and I/V for 1s.
What is the largest number you can write in Roman numerals?
Using standard notation, the largest number is 3,999 (MMMCMXCIX). There's no standard symbol for 5,000 or higher. Historically, a bar over a numeral multiplied it by 1,000 (V̄ = 5,000), but this isn't commonly used today.
Why is 4 written as IV instead of IIII?
Subtractive notation (IV) is shorter and became standard. A smaller numeral before a larger one means subtraction: IV = 5-1 = 4. However, IIII was historically valid and is still used on many clock faces for aesthetic balance with VIII on the opposite side.
Is there a Roman numeral for zero?
No, the Roman numeral system has no symbol for zero. The Romans used the word 'nulla' (meaning 'none') when needed. This is one reason why Arabic numerals replaced Roman numerals for mathematics—Arabic numerals include zero and a place-value system.