Roman Numeral Converter
Year Converter
Enter any year to see it in Roman numerals — useful for film credits, building dates, and anniversaries.
The Seven Roman Numeral Symbols
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
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?
What is subtractive notation in Roman numerals?
What is the largest number you can write in Roman numerals?
Where are Roman numerals used today?
What year is 2025 in Roman numerals?
Why can you not have more than three identical Roman numeral symbols in a row?
Related Calculators
Official Sources
Data verified against official UK government sources. Last checked April 2026.