How to convert roman numerals
Type the decimal or the roman numeral: the other box updates at once. Useful for study, clocks, chapters and classic dates. Range is 1–3999 (I to MMMCMXCIX).
Ontoom
Roman numerals
Convert decimal to roman and roman to decimal — as you type.
Conversion
2026 = MMXXVI
Important: Accepts 1 to 3999 (I to MMMCMXCIX). Everything runs in the browser.
Frequently asked questions
- What is the largest roman numeral accepted?
- 3999, written MMMCMXCIX. Above that the classic system is no longer standard.
- Does conversion work both ways?
- Yes. Decimal becomes roman and roman becomes decimal as you type.
- Do I need the internet after the page loads?
- No. The calculation runs in your browser.
- Do lowercase letters work?
- Yes. i, v, x, l, c, d and m are accepted as I, V, X, L, C, D and M.