Roman Numeral Calculator
Roman and Arabic place values
| Roman segment | Arabic value |
|---|---|
| Enter a value to see place values. | |
Roman numerals chart
The table below shows core symbols and the input format used for overline values (multiply by 1,000).
| Roman symbol | Value | Input format |
|---|---|---|
| I | 1 | I |
| V | 5 | V |
| X | 10 | X |
| L | 50 | L |
| C | 100 | C |
| D | 500 | D |
| M | 1,000 | M |
| I̅ | 1,000 | _I |
| V̅ | 5,000 | _V |
| X̅ | 10,000 | _X |
| L̅ | 50,000 | _L |
| C̅ | 100,000 | _C |
| D̅ | 500,000 | _D |
| M̅ | 1,000,000 | _M |
How this calculator works
The calculator treats each input as a full numeral expression, then resolves it to an exact integer result. Roman input is parsed with additive and subtractive rules, and number input is converted back to canonical Roman output.
Roman numerals do not represent fractional values, so number input accepts whole integers only.
Rules and limits
- Supported range: 1 to 3,999,999.
- Standard symbols: I, V, X, L, C, D, M.
- Subtractive pairs follow standard Roman rules such as IV, IX, XL, XC, CD, and CM.
- Values above 3,999 use overline notation. You can type either a bar-over character (for example L̅) or underscore format (for example _L) for 50,000.
Why a structured conversion matters
Roman numerals are not positional like base-10 numbers. They combine symbols by order and subtraction rules, which means direct text matching is not enough for reliable conversion.
This page uses deterministic conversion logic both ways, so you can move between Roman and Arabic formats quickly without manual checks.
Common use cases
- Books, chapters, and document front matter
- Clock faces and decorative numbering
- Historical references and inscriptions
- Date or event styling in formal layouts