The seven letters
I is 1, V is 5, X is 10, L is 50, C is 100, D is 500 and M is 1000.
Letters are written largest first and added, so MMXXIV is 1000 + 1000 + 10 + 10 + 4.
Subtractive pairs
A smaller letter before a larger one is subtracted: IV is 4, IX is 9, XL is 40, XC is 90, CD is 400 and CM is 900.
Only those six pairs are allowed. IL is not a Roman numeral for 49; the standard spelling is XLIX.
Worked example
2024 is MMXXIV, and 3999 is MMMCMXCIX, the largest standard numeral.
Reading MMXXIV gives 2024, and reading IV gives 4.
Inputs for the Roman numerals calculator
Number or Roman numeral
Type digits for a number from 1 to 3999, or letters such as MMXXIV. Either direction works.
CALCULATOR QUESTIONS
Roman numerals calculator questions
What is 2024 in Roman numerals?
MMXXIV, which is 1000 + 1000 + 10 + 10 + 4.
Why is 4 IV and not IIII?
Standard Roman numerals use the subtractive form IV. IIII appears on some old clocks but is not the standard spelling.
What is the largest number I can convert?
3999. Larger values need a bar over the letter to multiply it by a thousand.
Is there a Roman numeral for zero?
No. Roman numerals start at I, so zero has no numeral.