Why is IIII rejected, and what does lenient mode accept?

The standard form writes four as IV and allows at most three of I, X or C in a row, so IIII, XXXX and CCCC are rejected, as are pairs such as IC or VX that subtract in a way the rules do not allow. Clock faces often show IIII, and some older texts use forms like VIIII. Turn on lenient mode to accept those: IIII, VIIII, XXXX, LXXXX, CCCC, DCCCC and the short endings IL, IC, XD, XM, ID and IM. The result tells you how it was read and gives the standard spelling.

How do I write numbers above 3,999?

Standard Roman numerals stop at MMMCMXCIX (3,999) because there is no symbol above M for 1,000 and M is not repeated more than three times. A common convention puts a line over a letter to multiply it by 1,000, or writes the part in brackets, so 4,000 is (IV) and 3,999,999 is (MMMCMXCIX)CMXCIX. This is a convention, not a single standard, which is why the page shows both forms and asks you to turn it on.

Why is there no zero, and what about negatives and fractions?

Roman numerals were used for counting and recording amounts, and they have no symbol for zero or for negative numbers. Medieval writers who needed to say "none" in Roman-numeral tables wrote the word nulla, sometimes shortened to N. The Romans did write some fractions in twelfths with dots and the letter S, but there is no single modern convention, so this page converts whole numbers only and says so when you try 0, a negative number or a fraction.

Is anything I type uploaded?

No. The conversion runs in your browser, no request is made while you use it, and nothing is stored. Closing or refreshing the page clears the boxes.

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Roman numeral converter

Type a number like 2026 or a Roman numeral like MMXXVI and the other form appears, with the sum written out. Wrong spellings such as IIII or IC are rejected with the reason, and a lenient mode accepts them and says what it changed. It also writes dates and years, lists numbers from A to B, and reaches 3,999,999 with the overline convention. Everything runs in your browser and nothing is uploaded.

A number or a Roman numeral

Type either one. The page works out which way to convert. Lowercase is fine.

Try:

Lenient mode

Also accept clock-style IIII, additive forms such as VIIII and CCCC, and short endings such as IC for 99. The result says what it changed.

Allow numbers above 3,999

Uses the overline or bracket convention, up to 3,999,999. These forms are conventions, not one standard.

Result

Roman numeral

MMXXVI

How it adds up

2,026 = 1000 + 1000 + 10 + 10 + 5 + 1

The seven symbols

Letter	Value
I	1
V	5
X	10
L	50
C	100
D	500
M	1,000

The rules

•Write the biggest symbols first and add them up: XVI is 10 + 5 + 1 = 16.
•I, X and C can be repeated up to three times in a row (III is 3, XXX is 30). V, L and D are never repeated.
•A smaller symbol written before a bigger one is subtracted, but only in six pairs: IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900).
•There is no zero, and no negative numbers. The standard form stops at 3,999 (MMMCMXCIX).
•Each decimal digit is written on its own, thousands first: 1994 is M, CM, XC, IV.

Dates in Roman numerals

Enter a day, month and year, and choose how to write it. The year is the part most people want, for example for a cornerstone or a copyright line.

Day

Month

Year

Order

Separator

Roman numerals for

Date

Fill in the day, month and year.

Dates use the Gregorian calendar for every year, including years before it existed. Years from 1 to 3,999 only.

List numbers from A to B

Make a table of numbers and their Roman numerals, for a chapter list, a numbered outline or a quick reference. At most 4,000 rows.

From

How to use

•Type a numeral, in upper or lower case, to get the number. A non-standard spelling such as IIII, IC or VV is rejected, and the message says which rule it breaks.
•Turn on lenient mode to also accept the clock-style IIII, additive forms such as VIIII and XXXX, and short endings such as IL (49) and IC (99). It tells you what it read and gives the standard spelling.
•For numbers above 3,999, turn on the extended option: a line over a letter (or a pair of brackets) multiplies that part by 1,000, so 4,000 is I̅V̅ or (IV), up to 3,999,999. Books and software differ, so check which convention your reader expects.
•To write a date, type it as usual: 20/10/2026 becomes XX/X/MMXXVI, or keep the day and month as digits and write only the year.

Questions

Why is IIII rejected, and what does lenient mode accept?: The standard form writes four as IV and allows at most three of I, X or C in a row, so IIII, XXXX and CCCC are rejected, as are pairs such as IC or VX that subtract in a way the rules do not allow. Clock faces often show IIII, and some older texts use forms like VIIII. Turn on lenient mode to accept those: IIII, VIIII, XXXX, LXXXX, CCCC, DCCCC and the short endings IL, IC, XD, XM, ID and IM. The result tells you how it was read and gives the standard spelling.
How do I write numbers above 3,999?: Standard Roman numerals stop at MMMCMXCIX (3,999) because there is no symbol above M for 1,000 and M is not repeated more than three times. A common convention puts a line over a letter to multiply it by 1,000, or writes the part in brackets, so 4,000 is (IV) and 3,999,999 is (MMMCMXCIX)CMXCIX. This is a convention, not a single standard, which is why the page shows both forms and asks you to turn it on.
Why is there no zero, and what about negatives and fractions?: Roman numerals were used for counting and recording amounts, and they have no symbol for zero or for negative numbers. Medieval writers who needed to say "none" in Roman-numeral tables wrote the word nulla, sometimes shortened to N. The Romans did write some fractions in twelfths with dots and the letter S, but there is no single modern convention, so this page converts whole numbers only and says so when you try 0, a negative number or a fraction.
Is anything I type uploaded?: No. The conversion runs in your browser, no request is made while you use it, and nothing is stored. Closing or refreshing the page clears the boxes.