🏛️ Roman Numeral Converter
Convert between Roman numerals and numbers
Reference Table
I
1
V
5
X
10
L
50
C
100
D
500
M
1000
IV
4
IX
9
XL
40
XC
90
CD
400
CM
900
How Roman Numeral Conversion Works
- 1Enter a Roman numeral (e.g., XLII) or an Arabic number (e.g., 42).
- 2The converter maps symbols: I=1, V=5, X=10, L=50, C=100, D=500, M=1000.
- 3Subtractive notation is applied: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900.
- 4For Roman to Arabic: scan left to right, subtract when a smaller symbol precedes a larger one.
- 5For Arabic to Roman: repeatedly subtract the largest possible symbol value.
About Roman Numeral Converter
Convert between Roman numerals and Arabic numbers instantly. Supports numbers from 1 to 3,999. Learn the rules of Roman numeral notation with examples and a reference chart.
Frequently Asked Questions
What is the largest Roman numeral?
The standard system goes up to 3,999 (MMMCMXCIX). There is no single symbol for 5,000 or above. Historical extensions use a bar above letters to multiply by 1,000.
Why do clocks use IIII instead of IV?
This is tradition, not a rule. Some theories suggest IIII provides visual symmetry with VIII on the other side. Others say it honors Jupiter (IVPPITER in Latin).
Are there rules for Roman numerals?
Yes. A symbol can repeat up to 3 times (III=3). Only I, X, C, and M can repeat. Subtractive pairs are specific: IV, IX, XL, XC, CD, CM. You cannot write VV or LL.