Convert numbers to Roman numerals or Roman numerals to numbers with strict validation, running-total breakdowns, nearby-value checks.
Last updated
Roman numeral converter Use this Roman numeral converter to switch between decimal numbers and standard Roman numerals, check whether a numeral is valid, and see the running-total breakdown instead of only one final answer.
Standard notation rules used here This page accepts the seven standard symbols and the six standard subtractive pairs: IV, IX, XL, XC, CD, CM.
Clock faces may show `IIII`, but this converter follows the usual modern standard form instead.
Roman numeral
MMXXVI
2,026 in standard Roman numeral form is MMXXVI. It uses additive notation only.
Useful for date and copyright styling.
Canonical Roman form
MMXXVI
Expanded value
1,000 + 1,000 + 10 + 10 + 5 + 1
Running-total breakdown
Step
Value
Running total
1. M
1,000
1,000
2. M
1,000
2,000
3. X
10
2,010
4. X
10
2,020
5. V
5
2,025
6. I
1
2,026
Nearby values
Checkpoint
Decimal
Roman numeral
Previous
2,025
MMXXV
Current
2,026
MMXXVI
Next
2,027
MMXXVII
How to use the breakdown For number-to-Roman conversion, each row shows the next chunk added to build the numeral from left to right. For Roman-to-number conversion, the same rows show how the numeral accumulates into a decimal total, including subtractive pairs such as IV, IX, XL, XC, CD, and CM.
Roman numeral converter: number to Roman numeral and Roman to number
A Roman numeral converter helps you switch between standard Arabic numbers and Roman numerals without guessing whether a form is valid. This page works as both a number to Roman numeral converter and a Roman numeral converter to number, then shows the running-total breakdown so you can verify the answer instead of trusting a black-box result.
How a number to Roman numeral converter works
Standard Roman numerals use seven symbols: I, V, X, L, C, D, and M. A number to Roman numeral converter breaks the decimal value into chunks such as 1000, 900, 90, or 4, then writes the matching Roman groups from left to right.
That is why 1994 becomes MCMXCIV. The converter is not inventing a new pattern for each number. It is assembling standard building blocks in descending order: 1000 + 900 + 90 + 4, which map to M + CM + XC + IV.
1994 = 1000 + 900 + 90 + 4 = M + CM + XC + IV
A standard chunk-based way to build a Roman numeral from a decimal number.
How Roman to number conversion works
A Roman numeral converter to number reads the numeral from left to right, grouping valid subtractive pairs before adding the rest. In standard modern notation there are only six subtractive pairs: IV, IX, XL, XC, CD, and CM.
This matters because many invalid-looking strings can still seem plausible at first glance. IC is not a standard way to write 99, for example. The accepted standard form is XCIX, because X can subtract from C and I can subtract from X, but I does not jump directly to C in standard notation.
MCMXCIV = 1000 + 900 + 90 + 4 = 1994
Read the numeral as standard additive chunks after recognizing the subtractive pairs.
Roman numeral rules the converter checks
A good Roman numeral calculator should do more than swap symbols. It should validate the numeral against the usual modern standard: numerals are usually written from largest to smallest, only I, X, and C can appear in subtractive pairs, and the same symbol is not normally repeated more than three times in a row.
Those checks are why IV is valid but IIII is rejected on this page, even though clock faces often show IIII for stylistic balance. The calculator follows the standard modern form used in classrooms, outlines, dates, and most conversion tables.
Further reading
Britannica — Roman numerals — Reference overview of Roman numeral symbols, subtractive notation, and common modern uses.
Roman numerals still appear in book chapters, outlines, legal sections, clock faces, copyright dates, film sequel titles, and sports branding. That is why common searches include terms like Roman numeral date converter, how to write a year in Roman numerals, and Roman numeral chart.
A practical converter is useful because those real-world uses are not all the same. Some people need a quick answer for a chapter heading, some want to decode an old inscription, and others want to check whether a tattoo or engraved date is written in standard form.
Standard range and what happens above 3999
Most online Roman numeral converter tools limit standard notation to 1 through 3999. That upper limit is why MMMCMXCIX is usually treated as the largest standard modern numeral on simple conversion pages.
Larger values exist historically through extended conventions such as overlines, also called a vinculum, which multiply the value by 1000. Those forms are less standardized in modern everyday use, so this page stays focused on the standard range most users actually need.
Worked examples: 42, 99, and 2026
42 becomes XLII because 40 is XL and 2 is II. That is a good example of mixed subtractive and additive notation in one short numeral.
99 becomes XCIX, not IC. The correct split is 90 + 9, which gives XC + IX. A strong Roman numeral calculator should make that distinction visible because invalid shortcuts are one of the most common user mistakes.
2026 becomes MMXXVI, which is a useful year-style example. It shows two thousands, two tens, a five, and a one, all written in descending order without needing any subtractive pair.
Frequently asked questions
How do I convert a number to a Roman numeral?
Break the decimal number into standard Roman chunks such as 1000, 900, 90, and 4, then write the matching symbols from left to right. For example, 1994 = 1000 + 900 + 90 + 4, so the numeral is MCMXCIV.
How do I convert a Roman numeral to a number?
Read the numeral from left to right, recognize any valid subtractive pairs first, and then add the chunk values. For example, MCMXCIV = 1000 + 900 + 90 + 4 = 1994.
Why does this converter reject IIII for 4?
This page follows standard modern notation, where 4 is written as IV. Clock faces often use IIII for stylistic and historical reasons, but that is treated as an exception rather than the normal conversion rule.
Why is 99 written as XCIX instead of IC?
Standard Roman numeral subtraction only allows six pairs: IV, IX, XL, XC, CD, and CM. Because I cannot subtract directly from C in standard form, 99 is written as XCIX (90 + 9), not IC.
What is the largest number this Roman numeral converter supports?
This page supports the standard modern range from 1 to 3999. The largest standard numeral in that range is MMMCMXCIX. Larger values can be written with extended conventions such as overlines, but those are less standardized.
Is there a Roman numeral for zero?
No standard Roman numeral represents zero. Roman numerals were designed for counting and labeling values, not for a positional number system with a zero digit.
Can I use Roman numeral Unicode characters instead of normal letters?
For most purposes, plain Latin letters are the safer choice. Unicode includes dedicated Roman numeral symbols mainly for compatibility and certain layout cases, but ordinary letter sequences such as MMXXVI are generally preferred.
