Roman numeral converter

How Roman numerals work

Letters are written from largest to smallest and added up: VIII = 5 + 1 + 1 + 1 = 8. To avoid writing four of the same letter, a smaller letter placed before a larger one is subtracted. In the standard form used today, only six of these pairs are used:

• IV = 4 and IX = 9 (I before V or X)
• XL = 40 and XC = 90 (X before L or C)
• CD = 400 and CM = 900 (C before D or M)

The other rules follow from that: I, X, C and M appear at most three times in a row; V, L and D are never repeated or subtracted; and only one letter is subtracted at a time, so 8 is VIII, not IIX. The largest number in standard form is 3,999, MMMCMXCIX. The converter checks each of these rules and tells you which one a numeral breaks.

Bigger numbers: one common convention puts a bar (overline, also called a vinculum) over letters to multiply them by 1,000, so V̅ = 5,000 and X̅I̅I̅CCCXLV = 12,345. Historical usage varied, so treat this as a convention rather than a rule. The overline option writes thousands this way from 4,000 up to 3,999,999.

Zero: there is no Roman numeral for zero. Some medieval writers used the word nulla, or just N, in tables.

Worked examples

• 1994 = 1000 + 900 + 90 + 4 = M + CM + XC + IV = MCMXCIV.
• 2026 = 1000 + 1000 + 10 + 10 + 5 + 1 = MMXXVI.
• MMXXVI read back: M (1000) + M (1000) + X (10) + X (10) + V (5) + I (1) = 2026.
• IC is not standard: I can only be subtracted from V or X. 99 = 90 + 9 = XCIX.
• 14 November 2026 as day.month.year: 14 = XIV, 11 = XI, 2026 = MMXXVI, so XIV.XI.MMXXVI.

Where you see them

• Clock faces often show 4 as IIII instead of IV, a long tradition. The converter accepts IIII as 4 but points out the standard form.
• Years in film and TV credits, on buildings and on monuments, such as MCMXCIV for 1994.
• Names and events: monarchs and popes (Elizabeth II), sequels, and numbered events.
• Outlines and lists: chapters, prefaces (often in lower case: i, ii, iii, iv) and legal clauses.
• Dates for tattoos and engravings. Pick the order people will read correctly: day.month.year is usual in most of the world, month.day.year in the US. Check the result twice before it is permanent.

Fonts

The display styles use Cinzel and Marcellus, served from this site under the SIL Open Font License 1.1. See the font licences and copyright notices.

FAQ

How do you write 2026 in Roman numerals?

MMXXVI: two M (2,000), two X (20), V (5) and I (1).

What is the biggest Roman numeral?

In the standard form, 3,999 (MMMCMXCIX), because M is not written more than three times in a row. With the overline convention for thousands you can go much higher; this tool goes to 3,999,999.

Is IIII or IV correct for 4?

IV is the standard form today. IIII is common on clock faces and was used in ancient Rome too, so you will see both.

Why is 99 not IC?

In the standard form, I is only subtracted from V and X, X only from L and C, and C only from D and M. So 99 is written as 90 + 9, XCIX.

How do I type the overline?

The copy button adds a combining overline character (U+0305) after each letter, which most apps show as a bar. Some fonts draw it slightly off; if it looks wrong, write the thousands in brackets or spell out the number.

Is anything I type stored?

No. Everything is converted in your browser and nothing is saved.