# Roman Numerals Guide

Convert between Roman numerals and decimal numbers.

- Tool: https://ilham.dev/tools/roman-numeral/
- Guide URL: https://ilham.dev/guides/roman-numeral/
- Tool guides index: https://ilham.dev/guides/tools/
- Broader guide: Calculators and Unit Conversion (https://ilham.dev/guides/calculators-and-unit-conversion/)

## What it does

Convert between Roman numerals and decimal numbers, using the subtractive notation for 4, 9, 40, 90, 400 and 900. It covers 1 to 3999, which is the range the plain notation reaches without an overline.

## Use the tool

Open https://ilham.dev/tools/roman-numeral/, add the input the tool asks for, run it, and check the output before using it elsewhere.

## Input and output

- Input: text.
- Output: text.
- Category: Convert.

## Privacy and processing
Processing happens locally in your browser. This tool does not upload the input to ilham.dev.

## Questions

### Why does it stop at 3999?

Standard Roman notation has no zero and no way to write larger numbers without an overline or a different convention. 3999 is MMMCMXCIX, the largest value the plain form expresses.