Document preparation
Roman Numeral Converter
Arabic ↔ Roman numerals
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Reference Table
I 1
V 5
X 10
L 50
C 100
D 500
M 1000
Quick guide
What can Roman Numeral Converter help you do?
Free Roman numeral ↔ Arabic number converter. Supports 1 to 3999.
Best for
Check years, chapter numbers, or design copy using Roman numerals from 1 through 3999. The two independent converters use subtractive forms such as IV and IX. They do not cover overlined numerals, expanded ranges, or every historical spelling convention.
How to use it
Enter a plain integer from 1 to 3999 in the numeric field, or letters I, V, X, L, C, D and M in the Roman field. Both update independently. The initial examples are 2026 and MMXXVI; editing one input does not synchronize the other.
How to read the result
Roman input is uppercased and trimmed, evaluated, then converted back to verify the spelling. IV returns 4, while IIII and IL are rejected. Empty fields show a dash. The reference table lists the seven base symbols for checking each part of a result.
Privacy and limits
Conversion uses fixed tables in the browser. This widget makes no external lookup requests and has no local history storage. Enter only the number or numeral needed, rather than the document it came from, especially when other people can see your screen.
Use plain decimal integers from 1 through 3999. Fractional and scientific-notation strings are rejected rather than truncated. Zero, negative values and clock-face IIII are outside the accepted forms, not evidence that every historical alternative is wrong. Some error messages currently remain in Traditional Chinese.
Frequently Asked Questions
How to read Roman numerals?
I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Subtractive: IV=4, IX=9, XL=40.
Max value is 3999?
Standard Roman numerals max at MMMCMXCIX (3999). Larger requires special notation.