Roman Numeral Converter — Numbers to Roman & Back
How it breaks down
Symbol values
I 1
V 5
X 10
L 50
C 100
D 500
M 1000
Type a number to see its Roman numeral, or type a Roman numeral to get the number — the two fields stay in sync as you type. It handles values from 1 to 3999 (I to MMMCMXCIX), validates the notation, and shows how each result breaks down by place. Everything runs in your browser.
How it works
- 1 Type a number or a numeral Enter a whole number from 1 to 3999 in the number box, or type a Roman numeral like MMXXIV in the other box. Lowercase letters are accepted and converted for you.
- 2 Read the matching value The opposite field updates instantly. Enter 2024 and you get MMXXIV; enter MCMLXXXIV and you get 1984.
- 3 Check the breakdown Below the fields you'll see how the numeral is assembled — for example MM + XX + IV — which makes it easy to learn or double-check the notation.
Your data stays private
All processing happens entirely in your browser. No files, text, or data are ever sent to our servers. You can disconnect from the internet and this tool will still work.
Frequently asked questions
- What is the largest Roman numeral this supports?
- 3999, written MMMCMXCIX. Standard Roman numerals top out there because there's no single symbol above M (1000), so 4000 would need four M's, which the classic rules avoid. Larger numbers historically used a bar (vinculum) over a symbol to multiply it by 1000.
- Why is there no Roman numeral for zero?
- The Roman system is additive and had no concept of zero as a number. Scribes used the Latin word 'nulla' (none) when they needed to express nothing. That's why the converter starts at 1.
- What does the subtractive rule mean?
- When a smaller symbol comes before a larger one, you subtract it: IV is 4 (5 − 1), IX is 9, XL is 40, CM is 900. That's why 4 is IV rather than IIII, and the tool flags IIII as invalid.
- Can I type Roman numerals in lowercase?
- Yes. Type mcmxcix and it's read as MCMXCIX (1999). The converter uppercases your input automatically and ignores stray spaces.
- How do I write the current year in Roman numerals?
- 2026 is MMXXVI — two thousands (MM), twenty (XX), five (V), and one (I). Just type 2026 into the number box to confirm any year.