Roman Numeral Converter
Convert numbers to Roman numerals and Roman numerals to numbers. 100% client-side — works offline.
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2026=MMXXVI
📊 Step-by-Step Breakdown
M×2=2000
X×2=20
V×1=5
I×1=1
📖 Common Values Reference
🔒 100% private: All conversion happens in your browser. Works offline after first load.
About Roman Numeral Converter
Roman numerals are a numeral system from ancient Rome that uses combinations of letters (I, V, X, L, C, D, M) to represent numbers. They are still used today in various contexts: movie release years, clock faces, chapter numbers in books, sporting events (Super Bowl XLII), monarch names (Queen Elizabeth II), and tattoo designs. Roman numerals follow specific rules — subtractive notation (IV for 4, not IIII) and maximum 3 repeats (III for 3, but IV for 4). This tool converts any number from 1 to 3,999,999 to Roman numerals and decodes Roman numerals back to numbers. It validates input, shows the step-by-step breakdown, and includes a reference table for common values.
How It Works
- Number → Roman: Type a number (1–3,999,999) and see the Roman numeral instantly.
- Roman → Number: Type a Roman numeral (e.g., MMXXVI) and see the number.
- Both directions update live — type in either field.
- Copy any value, or use the reference table for quick lookup.
✨ Key Features
- ✓Number → Roman numeral conversion (1 to 3,999,999)
- ✓Roman numeral → Number conversion
- ✓Support for extended notation (with overlines for 4,000+)
- ✓Live bidirectional conversion
- ✓Validation with helpful errors
- ✓Step-by-step breakdown of conversion
- ✓Reference table of common values
- ✓Case-insensitive input (xiv = XIV)
- ✓Handles subtractive notation correctly
- ✓100% client-side — no data sent to any server
🎯 Common Use Cases
- →Converting years to Roman numerals (MMXXVI)
- →Reading copyright dates in old films
- →Understanding chapter numbers in books
- →Deciphering clock faces and monuments
- →Creating Roman numeral tattoo designs
- →Homework and study for Latin/history classes
- →Generating numbers for event editions (Super Bowl, Olympics)
- →Converting monarch regnal numbers
💡 Advanced Tips & Pro Insights
- ▸Standard Roman numerals cover 1 to 3,999. Above 3,999, an overline (vinculum) is used to multiply by 1,000. For example, V̄ = 5,000, X̄ = 10,000. This tool uses Unicode combining overlines to display these.
- ▸Subtractive notation is the modern standard: 4 = IV (not IIII), 9 = IX (not VIIII). Ancient Romans sometimes wrote IIII and VIIII, which you see on some old clocks.
- ▸The largest number representable in classic Roman numerals is 3,999 (MMMCMXCIX) — because you cannot have more than 3 M's in a row.
- ▸Zero was not represented in Roman numerals. The concept of "nulla" (Latin for "none") was introduced in medieval times.
- ▸Only 7 letters are used: I (1), V (5), X (10), L (50), C (100), D (500), M (1000).
Frequently Asked Questions
Is this Roman numeral converter free?▾
Yes, this Roman numeral converter is completely free with no signup, email, or usage limits.
Is my data safe?▾
Yes, 100% safe. All conversion happens in your browser. No data is sent to any server.
What is the largest number Roman numerals can represent?▾
In classic notation, 3,999 (MMMCMXCIX) is the largest. With overlines (vinculum) for values ×1,000, you can represent much larger numbers. This tool supports up to 3,999,999 using overline notation.
Why is 4 written as IV and not IIII?▾
This is called subtractive notation. To avoid four identical symbols in a row, 4 is written as IV (5 minus 1) rather than IIII. The same applies to 9 (IX), 40 (XL), 90 (XC), 400 (CD), 900 (CM).
What do the Roman numeral letters represent?▾
I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1,000. These are the only letters used in standard Roman numerals.
How do I write a year in Roman numerals?▾
Convert the year as a number. For example, 2026 = MMXXVI (M+M+XX+VI = 1000+1000+20+6).
What does the overline mean in Roman numerals?▾
An overline (called a vinculum) multiplies the value by 1,000. So V̄ = 5,000, X̄ = 10,000, M̄ = 1,000,000. This tool displays overlines using Unicode combining characters for large values.
Why did clocks use IIII instead of IV?▾
Historically, some clockmakers used IIII instead of IV for symmetry — it balances the VIII on the opposite side. The "watchmaker's four" (IIII) is still common today on traditional clocks.