Roman numeral converter
Fast, privacy-first online Roman numeral converter tool. 100% in-browser client-side execution with zero signups and zero data tracking.
1. Number or Date Input
Type any Arabic number (1 to 3,999) or Roman numeral (e.g. XIV, MCMLXXXIV) to convert instantly.
2. Converted Result & Expansion
Subtractive & Additive Breakdown
Roman Numeral Base Values
About this tool
How to use it
- Select your conversion mode: 'Standard Number' for integers or 'Calendar Date' for birthdates and commemorative anniversaries.
- Type an Arabic integer (1 to 3,999) or a Roman numeral string (e.g. MMXXVI or XIV) to convert in real time.
- Inspect the mathematical breakdown tokens showing how each digit decomposes into additive and subtractive Roman symbols.
- In Date mode, select your date and preferred separator (middle dot, dash, or slash) to generate tattoo-ready Roman date strings.
- Click 'Copy Result' to copy the converted Roman numeral or Arabic number to your clipboard.
Why it matters
Roman numerals remain widespread in architecture, film copyright dates, clock faces, book chapters, the Olympic Games, Super Bowl titles, and commemorative anniversary tattoos. Because Roman numerals follow a subtractive notation (IV for 4, IX for 9) rather than pure positional base-10 arithmetic, manual conversion is prone to syntax errors.
When to use it
Use when converting birthdates or wedding anniversaries for tattoos, reading building foundation stones and copyright years, preparing history lesson homework, or decoding monarch names (e.g., Charles III).
Good to know
Standard classical Roman numerals cap at 3,999 (MMMCMXCIX). In antiquity, numbers 4,000 and above were written with an overline (vinculum) to multiply by 1,000.
Common questions
How do you write 2026 in Roman numerals?
2026 in Roman numerals is written as MMXXVI (2000 = MM, 20 = XX, 6 = VI).
What are the 7 basic Roman numeral letters and their values?
The seven primary Roman numerals are: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, and M = 1,000.
What is subtractive notation in Roman numerals?
Subtractive notation places a smaller numeral before a larger numeral to subtract its value. For example, IV is 5 - 1 = 4, IX is 10 - 1 = 9, XL is 50 - 10 = 40, and CM is 1,000 - 100 = 900.
Why is 4 written as IV instead of IIII?
While Roman stone carvers and clockmakers historically used IIII, the standard subtractive rule adopted in late antiquity and modern typography uses IV to avoid repeating the same letter more than three times consecutively.
Does this tool work completely offline?
Yes. All conversion algorithms, date formatting, and grammar expansions run 100% locally in your web browser memory with zero network requests.