Roman numerals converter.

The Roman numerals converter turns any number from 1 to 3999 into Roman numerals and back, and works out the direction from what you type. The year 2026 is MMXXVI (MM + XX + VI), and MCMXCIV is 1994. Only the standard modern form is accepted, so IIII is flagged and corrected to IV. For years, the tool also names the century.

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Convert Roman numerals

Type a number (2026) or a Roman numeral (MMXXVI). The tool works out which way to convert.

Examples
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Enter a number from 1 to 3999 or a Roman numeral

The rules of Roman numerals

SymbolValue
I1
V5
X10
L50
C100
D500
M1000
  • Equal symbols add up, up to 3 in a row: III is 3, XXX is 30.
  • A smaller symbol before a larger one subtracts: IV is 4, IX is 9, XL is 40, XC is 90, CD is 400, CM is 900.
  • Only I, X, and C can subtract, and only from the next two symbols up (I from V and X, X from L and C, C from D and M).
  • V, L, and D never repeat and never subtract.
1994 = M + CM + XC + IV = 1000 + 900 + 90 + 4 = MCMXCIV

Years and centuries in Roman numerals

YearRoman numeralCentury
1776MDCCLXXVIXVIII
1865MDCCCLXVXIX
1969MCMLXIXXX
2000MMXX
2026MMXXVIXXI
Century N runs from year (N−1)×100 + 1 to year N×100, so the year 2000 is still in the 20th century

You see Roman numerals in movie copyright dates, on clock faces, in book chapters and outlines, in monarch names such as Henry VIII, and in Super Bowl numbers: Super Bowl LVIII is 58 (L + V + III). To measure the time between two years, use the days between dates calculator.

Old forms and the overline

The tool is strict and accepts only the standard modern form. IIII, VIIII, VX, IC, and IIX are rejected, and the message suggests the right spelling.

Some of those forms were real. IIII shows up on clock faces and in old inscriptions, and ancient writers used subtraction more loosely. In modern text, the standard is IV.

Above 3999, tradition draws a bar over a letter to multiply it by 1,000 (a V with a bar is 5,000). That notation is not converted here.

Curious about other number systems? Try the number base converter for binary and hex, or the unit converter for miles, pounds, and gallons.

Frequently asked questions

How do you write 2026 in Roman numerals?

2026 is MMXXVI: MM (2000) + XX (20) + VI (6). The tool converts any number from 1 to 3999.

Why is IIII wrong?

In standard form, 4 is written IV, and no symbol repeats more than three times. IIII appears on some clocks, but the tool treats IIII as an old form and suggests IV.

Is there a zero in Roman numerals?

No. The Roman system has no symbol for zero, so conversion starts at 1.

What is the largest Roman numeral?

Without an overline, the largest is MMMCMXCIX, which equals 3999. Bigger values use a bar over the letter.

How do I find the century of a year written in Roman numerals?

Divide the year by 100 and round up. The year 1776 is in the 18th century (XVIII), and 2026 is in the 21st century (XXI).

Sources and method

Standard public-domain formulas. Every calculation is checked against independent numeric tests before it goes live.