# Roman Numeral Converter - Numbers to Roman Numerals and Back

> Free online Roman numeral converter: a number to its Roman numeral or back, with validation of standard notation, a symbol-by-symbol breakdown and a table.

- URL: https://qilingtools.com/en/math/roman
- Category: Math Tools (https://qilingtools.com/en/math)
- Tags: [Math](https://qilingtools.com/en/tags/math), [Converters](https://qilingtools.com/en/tags/convert)
- Last updated: 2026-10-26
- Price: Free, no sign-up
- Privacy: Runs locally in the browser; files are never uploaded

The same box takes either a number or a Roman numeral and converts in the right direction automatically. Every result is broken down symbol by symbol, with a reference table and the subtraction rules alongside.

## How to use

1. Type a number (2024) or a Roman numeral (MMXXIV)
2. The conversion and the breakdown appear instantly
3. Copy the result in one click

## Features

- Automatic direction detection — no mode to pick
- Validates the notation, rejecting forms like IIII or IM
- Shows the value of each symbol
- Reference table and subtraction rules included

## FAQ

### How large can Roman numerals go?

Standard notation covers 1 to 3999. Larger values need an overline meaning ×1000, which is rarely used on the web and is not supported here.

### Why is IIII rejected?

In standard notation a symbol repeats at most three times, so 4 is IV. The tool regenerates the numeral to check it and flags non-standard spellings.

### What is the subtraction rule?

A smaller symbol before a larger one subtracts, and only six pairs are allowed: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900.

### Is there a Roman numeral for zero?

No — the system has no symbol for zero, so only whole numbers from 1 upwards can be written.

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