Roman Numeral Converter

Roman numeral converter at a glance#

A Roman numeral converter changes a number between Arabic form (like 2025) and Roman form (like MMXXV). Roman numerals use seven letters: I is 1, V is 5, X is 10, L is 50, C is 100, D is 500, and M is 1000. You read them left to right, adding the values.

When a smaller letter sits before a larger one, you subtract it. That gives the six subtractive pairs: IV is 4, IX is 9, XL is 40, XC is 90, CD is 400, and CM is 900. So 49 is XL plus IX, written XLIX, and 2024 is MM plus XX plus IV, written MMXXIV. A letter repeats at most three times in a row.

Enter a number or a Roman numeral in the converter above for the exact result either way. Standard Roman numerals have no zero and run from 1 to 3999; a bar over a letter multiplies it by 1000 for larger values.

The rules for reading Roman numerals#

Roman numerals use seven letters: I is 1, V is 5, X is 10, L is 50, C is 100, D is 500, and M is 1000. You read them left to right and add the values, so XVI is 10 + 5 + 1 = 16. When a smaller letter sits before a larger one, you subtract it: IV is 4 and IX is 9.

A letter repeats at most three times in a row, so XXX is 30 but 40 is not XXXX. There is no symbol for zero. A bar over a letter multiplies it by 1000, so X with a bar is 10,000 and V with a bar is 5,000, which is how values above 3,999 are written.

The six subtractive pairs#

Only six pairs use subtraction. Memorize these and the rest follow.

Writing dates and years#

Convert a year the same way as any number, working from the largest value down. 2023 is MM (2000) + XX (20) + III (3), which is MMXXIII. 1994 is M (1000) + CM (900) + XC (90) + IV (4), which is MCMXCIV. 2025 is MMXXV.

Frequently asked questions#

How do I read Roman numerals?#

Add the letter values from left to right, but subtract a smaller letter that comes before a larger one. XII is 12, and XIV is 14 (10 + 4).

What are the seven Roman numeral symbols?#

I (1), V (5), X (10), L (50), C (100), D (500), and M (1000). Every Roman numeral is built from these.

How does subtractive notation work?#

A smaller letter before a larger one is subtracted. There are only six such pairs: IV (4), IX (9), XL (40), XC (90), CD (400), and CM (900).

How are large numbers written?#

Combine symbols from largest to smallest, so MMXX is 2020. For values above 3,999, a bar over a letter multiplies it by 1000, so V with a bar is 5,000.

Why is there no zero in Roman numerals?#

The system is additive and has no place value, so it never needed a zero. A quantity of zero is simply left out.

How do I convert a date to Roman numerals?#

Write the whole year as one number from the largest value down. 2023 is MMXXIII, and 1994 is MCMXCIV.