Roman Numerals Calculator
Instantly convert standard integers to Roman numerals and decode ancient Roman numerals back to modern numbers with step-by-step breakdowns.
Convert Numbers & Numerals
Select your conversion direction and enter a value to instantly translate between modern Arabic numerals and ancient Roman numerals.
Numeral Converter
Supports standard values from 1 to 3,999 (MMMCMXCIX).
How it Works
Roman numeral rules
Base Symbols
Seven letters represent values: I (1), V (5), X (10), L (50), C (100), D (500), and M (1000).
Additive Rule
When a smaller or equal numeral follows a larger one, you add their values (e.g., VI = 5 + 1 = 6).
Subtractive Rule
When a smaller numeral precedes a larger one, you subtract it (e.g., IV = 5 – 1 = 4, IX = 10 – 1 = 9).
Repetition Limits
Symbols I, X, C, and M can be repeated up to three times in a row. V, L, and D are never repeated.
Standard Symbol Chart
A quick reference table for the seven basic symbols used in the Roman numeral system and their corresponding integer values.
| Symbol | Name | Integer Value | Example Usage |
|---|---|---|---|
| I | Unus | 1 | II = 2, III = 3 |
| V | Quinque | 5 | VI = 6, VIII = 8 |
| X | Decem | 10 | XX = 20, XXX = 30 |
| L | Quinquaginta | 50 | LX = 60, LXXX = 80 |
| C | Centum | 100 | CC = 200, CCC = 300 |
| D | Quingenti | 500 | DC = 600, DCCC = 800 |
| M | Mille | 1,000 | MM = 2000, MMM = 3000 |
Roman Numerals FAQ
Answers to the most frequently asked questions about reading, writing, and converting Roman numerals.
Roman numerals are a numeric system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers in this system are represented by combinations of letters from the Latin alphabet: I, V, X, L, C, D, and M.
In Roman numerals, 4 is written as IV (5 minus 1) and 9 is written as IX (10 minus 1). This uses the subtractive notation rule, where a smaller numeral placed before a larger numeral indicates subtraction rather than addition.
The Roman numeral system was designed for commerce and counting tangible objects, not for complex mathematics. The concept of zero as a number and a placeholder was not part of their mathematical framework. The concept of zero was later introduced to Europe via the Hindu-Arabic numeral system.
In standard modern usage, the highest number you can write is 3,999 (MMMCMXCIX). While the ancient Romans sometimes used overlines (vinculum) to multiply values by 1,000, standard calculators and modern conventions cap at 3,999 to maintain simplicity and consistency.