Convert any integer (1–3,999,999) to Roman numerals and back. Features batch conversion for lists of numbers, a range generator, validation with clear error messages, and a full value-table reference. Supports both standard subtractive notation and additive-only notation.
Type any integer from 1 to 3,999,999 in the Number field, or type a Roman numeral in the Roman field. Conversion is bidirectional and instant. The tool validates your input and shows a clear error if the number is out of range or the Roman numeral contains invalid characters.
Switch to Batch Mode to convert a whole list at once. Enter one number per line (or one Roman numeral per line for reverse batch). The output table shows both the input and converted value side by side. Copy or download the full table as CSV.
Use the Range Generator to convert every integer in a range (e.g. 1–100). Set start and end values and click Generate. The results table is downloadable as CSV — useful for reference sheets, educational materials, or clock-face designs.
Roman numerals are a numeral system that originated in ancient Rome. Seven symbols are used: I (1), V (5), X (10), L (50), C (100), D (500), and M (1000). Numbers are formed by combining these symbols and adding their values. The modern system uses subtractive notation: placing a smaller value before a larger one indicates subtraction (IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900). Additive-only notation (IIII for 4) was historically used on clock faces and some inscriptions.
Using the standard seven symbols (I, V, X, L, C, D, M), the maximum is 3,999 (MMMCMXCIX). To represent larger numbers, ancient Romans used a vinculum (horizontal bar over a numeral) to multiply by 1,000. This tool supports the vinculum notation for numbers up to 3,999,999 using parentheses notation: (M) = 1,000,000, (V) = 5,000, etc.
The standard rules are: I can precede V (IV = 4) and X (IX = 9). X can precede L (XL = 40) and C (XC = 90). C can precede D (CD = 400) and M (CM = 900). No other subtractive combinations are standard. For example, IL for 49 is not standard — the correct form is XLIX. Symbols may not be subtracted more than once in a sequence.
Roman numerals are still widely used for: clock and watch faces (I through XII), book chapters and volume numbers (Chapter IV), movie sequel numbers (Rocky IV, Star Wars Episode IX), year numbers in film and TV credits (MMXXIV), names of monarchs and popes (King Charles III, Pope Francis I), Super Bowl and Olympic Games (Super Bowl LVIII), and formal lists and outlines in academic writing.
Standard (subtractive) notation uses pairs like IV, IX, XL, XC, CD, CM to represent values ending in 4 or 9. Additive-only notation writes these values without subtraction: 4 = IIII, 9 = VIIII, 40 = XXXX, 90 = LXXXX. Clock faces traditionally use IIII instead of IV (possibly to balance the visual weight of VIII on the opposite side). This tool supports both modes — you can toggle between subtractive and additive output.
No. The Roman numeral system has no symbol for zero — this was one of its key limitations. The concept of zero was developed in India and transmitted to Europe through Arabic mathematics during the medieval period, eventually replacing Roman numerals for arithmetic. Romans did have a system for fractions based on twelfths (the uncia system, from which we get "ounce" and "inch"), but these are not represented in standard Roman numeral notation.
