Roman Numerals Converter (Number ↔ Roman, Free)

A Roman numerals converter turns numbers into Roman numerals and back by working one place value at a time. For example, 1994 = 1000 + 900 + 90 + 4 = M + CM + XC + IV, so 1994 is MCMXCIV. Reading the other way, MCMXCIV = 1000 + 900 + 90 + 4 = 1994.

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How to use the Roman numerals converter

1. Type a whole number (such as 2026) or a Roman numeral (such as XLIX) in the Convert tab. The converter detects the direction, so there is no switch to set. Lowercase letters are fine.
2. Read the answer, the breakdown tiles (one tile per place value) and the steps.
3. If a numeral is not valid, the converter says which rule it breaks and suggests the standard form, for example IIII → IV.
4. Use the Date tab for dates such as 07.04.1776, the Arithmetic tab to add, subtract, multiply or divide two numerals, and the Chart tab to list any range of numbers.

How Roman numerals work

Roman numerals use seven letters. Each has a fixed value, and the values are added from left to right, largest first.

To avoid four symbols in a row, a smaller symbol written before a larger one is subtracted. Only six of these subtractive pairs are standard: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900.

The quickest way to write any number is to split it into thousands, hundreds, tens and ones and write each part from this chart:

A zero digit is simply skipped, because there is no Roman zero.

Rules for a valid Roman numeral

The converter checks every numeral against the standard rules and explains any break:

• I, X, C and M may repeat, but at most three times in a row: III = 3, but 4 is IV, not IIII.
• V, L and D never repeat (VV would just be X) and are never subtracted (VX is not 5).
• I may stand only before V and X, X only before L and C, and C only before D and M. So 49 is XLIX, not IL, and 99 is XCIX, not IC.
• Only one smaller symbol may be subtracted: 8 is VIII, not IIX.
• Each place value is written once, from largest to smallest. IXI or XCX are not standard.

Clock faces often show IIII for 4. That is a design tradition; the standard form is IV.

Worked examples

Example 1: number to Roman numeral

Write 2026. Split it: 2026 = 2000 + 20 + 6. From the chart, 2000 = MM, 20 = XX and 6 = VI, and the hundreds digit is 0, so nothing is written for it. Joining the parts gives MMXXVI.

Example 2: Roman numeral to number

Read CDXLIV. Pair the subtractive symbols first: CD | XL | IV. That is 400 + 40 + 4 = 444. A check: writing 444 back gives CDXLIV, so the numeral is in standard form.

Example 3: adding Roman numerals

XLIV + XXIX: convert to 44 + 29 = 73, then write 73 = 70 + 3 = LXX + III = LXXIII. The Romans themselves added by writing all the symbols together and swapping groups (IIIII → V, VV → X), which gives the same answer.

Large numbers: the vinculum

Standard Roman numerals stop at 3,999 (MMMCMXCIX). For larger numbers, a bar over a numeral, called a vinculum, multiplies it by 1,000. So V̅ = 5,000, X̅ = 10,000, and M̅ = 1,000,000. The converter writes the thousands with a bar and the rest normally:

• 4,420 = I̅V̅ (4 thousands) + CDXX (420) = I̅V̅CDXX.
• 15,000 = X̅V̅.
• 3,999,999 = M̅M̅M̅C̅M̅X̅C̅I̅X̅CMXCIX, the largest value it writes.

The vinculum is a later convention, not part of the everyday classical system, and different books use slightly different styles. On a keyboard, type an underscore before each barred letter: _I_VCDXX.

Writing dates in Roman numerals

Convert the month, day and year separately and keep the date’s order. July 4, 1776 in US order (MM.DD.YYYY) is 7.4.1776 = VII.IV.MDCCLXXVI; in day-month-year order it is IV.VII.MDCCLXXVI. Leading zeros are dropped, since 07 is just 7. Dots or middle dots are the usual separators for engravings, rings and tattoos. Double-check the order before anything permanent: 03.04 means March 4 in the US but 3 April in most other countries.

Common mistakes with Roman numerals

Checking homework with the converter

Convert by hand first, place value by place value, then type your answer into the converter. If it reports a rule break, the message names the exact pair or repeat that is wrong. For practice in the other direction, type the number and compare each breakdown tile with your own work, or print a range from the Chart tab.

Roman numerals practice quiz: 10 questions

Test yourself with 10 multiple-choice questions. Choose an answer and press Submit to see if you are right and why. Your score appears at the end.

Frequently asked questions

How do you convert Roman numerals to numbers?

Read from left to right. When a symbol is smaller than the one after it, subtract it; otherwise add it. MCMXCIV is M (1000) + CM (900) + XC (90) + IV (4) = 1994.

What is 50 in Roman numerals?

50 is L. Nearby values build on it: 40 = XL, 55 = LV and 60 = LX.

What is XLV in Roman numerals?

XLV is 45: XL = 40 (ten before fifty) and V = 5. It is not 65, because the X is subtracted from the L.

What are 4 and 9 in Roman numerals?

4 is IV and 9 is IX: one before five, and one before ten. The same idea gives 49 = XLIX (40 + 9), not IL.

How do you read a Roman numerals chart?

Find each digit of your number in its place-value column and join the pieces from thousands down to ones. For 368: CCC (300) + LX (60) + VIII (8) = CCCLXVIII.

How do you write a date in Roman numerals?

Convert the day, month and year separately, then join them with dots. 14 March 1998 is XIV.III.MCMXCVIII in day-month-year order, or III.XIV.MCMXCVIII in US order.

Why is there no zero in Roman numerals?

Roman numerals record amounts by adding symbols, so an empty place is simply left out. Medieval writers sometimes used the word nulla (or N) for zero, but it is not part of the standard system.

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