Question 1

What is this tool used for?

Accepted Answer

It converts between Roman numerals (I, V, X, L, C, D, M) and decimal numbers (1–3999), using standard subtractive notation.

Question 2

What Roman format is supported?

Accepted Answer

Standard notation: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900. Input is case-insensitive.

Question 3

What range of numbers?

Accepted Answer

Decimal to Roman supports 1–3999. Roman to decimal accepts any valid Roman numeral in that range.

Question 4

Is conversion done on a server?

Accepted Answer

No. Conversion runs entirely in your browser.

Question 5

When should I use it?

Accepted Answer

Use it for outlines, copyright years, or learning Roman numerals.

Question 6

Why does Roman to decimal fail?

Accepted Answer

Ensure the string uses only I, V, X, L, C, D, M and follows standard order (e.g. no IIII for 4; use IV).

Roman Numeral Converter

Frequently Asked Questions