Roman Numeral Converter

Number → Roman

Roman → Number

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Year Converter

Enter any year to see it in Roman numerals — useful for film credits, building dates, and anniversaries.

Year

The Seven Roman Numeral Symbols

One

Five

Ten

Fifty

100

Hundred

500

Five Hundred

1000

Thousand

Subtractive Notation — The Six Special Cases

When a smaller symbol appears before a larger one, it is subtracted. Only these six combinations are valid:

Roman	Calculation	Value	Rule
IV	5 − 1	4	I before V
IX	10 − 1	9	I before X
XL	50 − 10	40	X before L
XC	100 − 10	90	X before C
CD	500 − 100	400	C before D
CM	1000 − 100	900	C before M

Reference Table: 1–100

Large Numbers: 100–3999

Roman Numeral Quiz

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Where Roman Numerals Are Used Today

Clock faces: Traditional analogue clocks often use I through XII (though some use IIII instead of IV)
Film dates: Film copyright dates are traditionally shown in Roman numerals (e.g. MMXXV for 2025)
Super Bowl: Each Super Bowl is numbered with Roman numerals (Super Bowl LIX = 59th)
Monarchy and popes: Henry VIII, Elizabeth II, Pope Francis I — Roman numerals denote regnal numbers
Book structures: Prefaces and introductions are often paginated in Roman numerals (i, ii, iii...)
Formal outlines: Documents use Roman numerals for main sections (I, II, III) then letters for subsections
Buildings: Cornerstones and dedications often display the year of construction in Roman numerals
Music: Chord progressions are notated using Roman numerals (I, IV, V chords)

A Brief History of Roman Numerals

Roman numerals evolved from a tally system used in ancient Rome from around the 4th century BCE. Early Romans used I for one (representing a single tally mark), V for five (the shape of an open hand), and X for ten (two Vs placed together or a crossed hand).

The system was used throughout the Roman Empire for commerce, military, and record-keeping. During the Middle Ages, Roman numerals remained dominant in Europe for formal documents, though Hindu-Arabic numerals (0–9) gradually replaced them for calculations from the 12th century onward.

Today, Roman numerals survive as a decorative and formal convention, carrying a sense of prestige and permanence — which is why they appear on monuments, diplomas, and major events.

How to Convert Roman Numerals

This converter provides instant, accurate results for your measurement conversions. The UK uses a mix of metric and imperial measurements in daily life, which can make conversions a frequent necessity. Road signs use miles, food is sold in grams and kilograms, and height is often quoted in feet and inches despite the metric system being the official standard.

Understanding the conversion formula helps verify results and perform quick mental calculations when a tool is not available.

Key Information

Common UK conversion factors: 1 inch = 2.54 cm, 1 foot = 30.48 cm, 1 mile = 1.609 km, 1 pound (lb) = 0.4536 kg, 1 stone = 6.35 kg, 1 pint (UK) = 568 ml, 1 gallon (UK) = 4.546 litres, 1 acre = 0.4047 hectares. Temperature conversions use the formula: Celsius = (Fahrenheit - 32) x 5/9.

Example Calculation

To convert 5 feet 10 inches to centimetres: first convert to total inches (5 x 12 + 10 = 70 inches), then multiply by 2.54 to get 177.8 cm. For weight, a person weighing 12 stone 7 lbs is 12.5 stone, which equals 79.4 kg (12.5 x 6.35).

Source: Based on international measurement standards. Last updated March 2026.

Frequently Asked Questions

What are the seven Roman numeral symbols?

The seven symbols are I=1, V=5, X=10, L=50, C=100, D=500, M=1000. All Roman numerals between 1 and 3999 are constructed from combinations of these seven symbols using additive and subtractive rules.

What is subtractive notation in Roman numerals?

Subtractive notation places a smaller symbol before a larger one to indicate subtraction. The six valid combinations are: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900. All other combinations are additive (the symbols are summed left to right).

What is the largest number you can write in Roman numerals?

The largest standard Roman numeral is 3999, written MMMCMXCIX. This is because M can appear at most three times (giving 3000), and the remaining maximum is 999 (CMXCIX). Ancient texts sometimes placed a bar over a numeral to multiply by 1000, allowing numbers up to 3,999,999.

Where are Roman numerals used today?

Roman numerals appear on traditional clock faces (I–XII), film copyright dates, Super Bowl numbering, monarch and pope names (Elizabeth II, Henry VIII), book prefaces and chapters, formal outlines, building cornerstones, diplomas, and in music theory for chord notation.

What year is 2025 in Roman numerals?

2025 in Roman numerals is MMXXV. The breakdown is: MM = 2000, XX = 20, V = 5. So 2000 + 20 + 5 = 2025 = MMXXV. Similarly, 2026 = MMXXVI, 2024 = MMXXIV, and 1999 = MCMXCIX.

Why can you not have more than three identical Roman numeral symbols in a row?

The three-identical-symbol rule exists to keep Roman numerals concise. Without it, you would write 4 as IIII (four symbols) instead of IV (two symbols). This rule applies to I, X, C, and M but not to V, L, or D — which can never appear more than once since they represent mid-values (5, 50, 500).