Practical tools for measured work
Roman numeral converter
Convert integers from 1 to 3999 to canonical Roman numerals and back.
Calculate the layout, check the diagram, then print the result for the shop or jobsite.
How it works
Convert integers from 1 to 3999 using I, V, X, L, C, D and M with standard subtractive pairs. Four is IV, nine is IX and 1994 is MCMXCIV. Roman input is case-insensitive and must match canonical notation.
Current-input example
The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.
- Conversion direction
- Number to Roman
- Integer
- 4
Primary result: Converted value: IV.
Before using the result
- Check the selected mode, units and input values before using the result.
- Read the assumptions and rounding rules; compare the worked example with your intended calculation.
- A numerical result does not supply missing context or change the stated limitations.
Limitations
Zero, negative numbers, fractions, overbars and historical additive variants are excluded. Noncanonical forms such as IIII and IC are rejected.
Frequently asked questions
Are the displayed decimals exact?
Fractions, combinations and integer multiples use exact integer arithmetic. Other results use floating-point arithmetic and are rounded for display. Keep the exact fraction when a repeating decimal matters.
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