Convert numbers to Roman numerals and back. Supports 1 to 3,999,999 with step-by-step breakdown.
Step-by-Step Breakdown
Free Online Roman Numeral Converter
Instantly translates between Arabic numbers (1, 2, 3) and Roman numerals (I, II, III). Perfect for students, historians, or anyone working with classical numbering systems.
Common Use Cases
Academic Writing — Number chapter headings and outline sections using Roman numerals as required by style guides.
Film & TV Credits — Convert production years to Roman numerals for copyright notices (e.g., MMXXVI for 2026).
Clock Faces — Understand Roman numeral markings on analog clocks (I through XII).
Book Editions — Decode edition numbers on title pages (e.g., Edition XV = 15th).
Royalty & Popes — Distinguish same-name rulers (Henry VIII, Pope John Paul II).
How It Works
Number → Roman: Breaks down your number into standard Roman values (M=1000, D=500, C=100, L=50, X=10, V=5, I=1) using subtractive notation (IV=4, IX=9, XL=40, etc.). For numbers ≥ 4,000, overlines multiply values by 1,000.
Roman → Number: Parses each symbol, adds values, handles subtractive pairs, and resolves overlines. Invalid input triggers an error message.
Quick Reference Examples
I
1
IV
4
V
5
IX
9
X
10
XL
40
L
50
XC
90
C
100
CD
400
D
500
CM
900
M
1,000
V̄
5,000
M̄
1,000,000
More Patterns
XLII
42
XCIX
99
CCCLXV
365
MCMXCIV
1994
MMXXVI
2026
MMMCMXCIX
3,999
How to Use the Roman Numeral Converter
Choose your conversion direction by clicking the mode buttons at the top. In "Number → Roman" mode, enter any integer between 1 and 3,999,999 and the converter instantly displays the Roman numeral equivalent with a step-by-step breakdown showing each place value. In "Roman → Number" mode, type a Roman numeral using standard notation (I, V, X, L, C, D, M) and the tool calculates the numeric value. For numbers above 3,999, the converter automatically uses overline notation — a bar above a letter multiplies its value by 1,000.
Common Use Cases for Roman Numerals
Academic Writing: Number outline sections, appendices, and preface pages using Roman numerals as required by APA, MLA, and Chicago style guides. Chapter headings in many textbooks use Roman numerals for a classic, scholarly appearance.
Film & Television Credits: Production companies display copyright years in Roman numerals at the end of movies and TV shows. Convert current year 2026 to MMXXVI for authentic-looking credit sequences.
Clock & Watch Design: Traditional analog clocks use Roman numerals I through XII for hour markings. Watchmakers and clock enthusiasts use this converter to verify accurate numeral placement on custom timepiece designs.
Historical Document Interpretation: Historians and students frequently encounter Roman numerals in ancient texts, legal documents, and monumental inscriptions. This converter helps decode dates, chapter numbers, and regnal years quickly.
Tips for Working with Roman Numerals
Remember the Subtractive Rule: A smaller numeral placed before a larger one means subtract (IV = 4, IX = 9, XL = 40). This is the most common mistake people make — writing IIII instead of IV for 4 is incorrect in modern usage.
Read Right to Left for Addition: When converting Roman to numbers, parsing from right to left is often easier. Start with the rightmost symbol as your base, then add or subtract each preceding symbol depending on whether it is larger or smaller.
Use the Breakdown Feature: The step-by-step breakdown shows how each place value contributes to the final numeral. This is especially helpful when learning the system or verifying complex conversions like MCMXCVIII (1998).
Frequently Asked Questions
What numbers can this converter handle?
Integers from 1 to 3,999,999, covering standard Roman numeral usage and extended notation with overlines.
How are large Roman numerals written?
Numbers beyond 3,999 use overlines (V̄ = 5,000, X̄ = 10,000) to multiply the base value by 1,000.
What is subtractive notation?
A smaller numeral before a larger one indicates subtraction (IV = 4, IX = 9). This medieval convention is now standard.
Why is there no zero in Roman numerals?
The ancient Romans had no concept of zero. The numeral system was additive, not positional.
Can I use this for years?
Yes. Enter any year to see its Roman numeral representation. MMXXVI = 2026.
Is this converter free to use?
Absolutely. Completely free with no limits or restrictions.
How do I write 1999 in Roman numerals?
1999 is written as MCMXCIX. It breaks down as M (1000) + CM (900) + XC (90) + IX (9). Note that it is not MIM — the subtractive notation only applies to specific pairs like CM, CD, XC, XL, IX, and IV.