Roman Numeral Converter

This converts Roman numerals to Arabic and back. It assumes standard Roman numeral positional notation. Prefix values are limited to the next lesser multiple of ten. The standard numeral range is I=1, V=5, X=10, L=50, C=100, D=500, M=1000. The extended range adds Y=5000, Z=10000, F=50000, H=100000, B=500000, and A=1000000. Some users of  Roman numerals used a bar over the standard value to indicate multiplcation by 1000. Use the extended range for these examples.
To convert from Roman to Arabic, enter the value in the box denoted Roman and then click anywhere outside the box or press the Enter key. To convert from Arabic to Roman, enter the value in the box marked Arabic and click or press Enter.

Roman numeral: 
Arabic numeral: