Roman Numeral to Decimal
Convert roman to number quickly with this free online calculator. The page explains the conversion rule, gives practical examples and provides a quick reference table.
Convert roman to number using the conversion factor used by this tool.
How to use the Roman Numeral to Decimal
- Enter the number you want to convert.
- Confirm the source unit shown beside the input.
- Choose decimal precision if you need more or less detail.
- Read the converted result.
- Copy the result when you need to use it elsewhere.
How the conversion works
Convert roman to number using the conversion factor used by this tool.
For a simple fixed-factor conversion, the calculator multiplies the entered value by the stated factor. Temperature scales and certain specialized tools use their specific mathematical relationship instead.
Common roman to number conversions
| roman | number |
|---|---|
| 1 roman | 1 number |
| 2 roman | 2 number |
| 5 roman | 5 number |
| 10 roman | 10 number |
| 20 roman | 20 number |
| 50 roman | 50 number |
Example
For example, entering 1 roman gives approximately 1 number using the rule above. Change the input to test your own value.
Frequently asked questions
Accuracy note: This calculator is a practical reference. For regulated, safety-critical or specialized work, verify the result against the applicable standard.
Page reviewed: August 24, 2026.