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Ancient Number System • Two-Way Conversion • Educational Tool
Roman Number ConverterConvert Roman Numerals to Arabic Numbers & Vice Versa • Complete Guide with Examples
Two-Way Conversion
Conversion History
Educational Guide
Real-Time Validation
Quick Example Conversions:
Real-time validation
Enter a number between 1 and 3999
Roman Numerals Complete Guide
I
= 1
IV
= 4
V
= 5
IX
= 9
X
= 10
XL
= 40
L
= 50
XC
= 90
C
= 100
CD
= 400
D
= 500
CM
= 900
M
= 1000
Essential Roman Numeral Rules:
Numerals must be written from largest to smallest (e.g., XVI=16, not XIVI)
I, X, C can be repeated up to 3 times (III=3, XXX=30, CCC=300)
V, L, D cannot be repeated - only appear once in a number
Subtraction only with I before V or X, X before L or C, C before D or M
Only one smaller numeral can precede a larger one (IV=4, not IIV for 3)
Conversion History
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About Roman Numerals
Roman numerals originated in ancient Rome around 500 BC and were used throughout the Roman Empire. This numeral system remained the standard in Europe until the late Middle Ages when Arabic numerals gradually replaced it.
Maximum number in standard system: 3999 (MMMCMXCIX)
No concept of zero - system starts from I (1)
Case insensitive in modern usage (IV = iv = Iv)
Combines additive and subtractive principles
Common Modern Uses:
Clock and watch faces (I-XII)
Book volumes, chapters, and page numbers
Movie production years and sequel numbering
Monument inscriptions and building cornerstones
Monarch and Pope names (Henry VIII, Pope John Paul II)