Base 2, 8, 10, 16 & Roman Numerals

Number System & Roman Numeral Converter

Convert numbers in real time between Decimal, Binary, Octal, Hexadecimal, and Roman Numerals with instant two-way synchronization and one-click copy buttons.

Dynamic Real-Time Number Converter

Type into any box below — all other numeral formats will update automatically in real time!

Quick Number Presets:

Mathematical Foundations of Positional Number Systems

A numeral system is a writing system for expressing numbers using mathematical symbols. Positional number systems use a base (or radix), where each digit's value depends on its position relative to the radix point.

Decimal (Base 10)

The standard counting system used by human civilization, utilizing ten digits from 0 to 9. Each digit represents a power of 10 (units, tens, hundreds, thousands).

Binary (Base 2)

The core computational language of modern microprocessors. Uses two voltage states represented by bits: 0 (Off) and 1 (On), representing increasing powers of 2.

Hexadecimal (Base 16)

Uses 16 distinct symbols: digits 0 through 9 followed by letters A through F (where A=10, B=11, C=12, D=13, E=14, F=15). Extensively used for memory dump addresses and CSS colors.

Roman Numerals

The additive and subtractive numeric system of ancient Rome. Widely used for clock faces, super bowl editions, regal names, and book volume chapter titles.

Roman Numeral Conversion Table & Subtractive Rules

The Romans utilized seven uppercase letters to represent quantities. When a symbol of lower value appears before a symbol of higher value, subtraction is performed:

Decimal (Base 10) Binary (Base 2) Octal (Base 8) Hexadecimal (Base 16) Roman Numeral
1 0001 1 1 I
4 0100 4 4 IV (5 - 1)
9 1001 11 9 IX (10 - 1)
16 10000 20 10 XVI
40 101000 50 28 XL (50 - 10)
90 1011010 132 5A XC (100 - 10)
255 11111111 377 FF CCLV
400 110010000 620 190 CD (500 - 100)
900 1110000100 1604 384 CM (1000 - 100)
2026 11111101010 3752 7EA MMXXVI

Frequently Asked Questions About Number Bases

Helpful answers regarding computer arithmetic and Roman numeral math.

Standard Roman numerals without vinculum overline bars natively support integers from 1 up to 3,999 (MMMCMXCIX). Numbers 4,000 and above historically required an overline representing multiplication by 1,000.

In Unix systems, file permissions (Read=4, Write=2, Execute=1) are neatly represented in 3-bit octal digits (e.g. 755 or 644). One octal digit directly encodes three permission flags.

Yes! Simply type any Roman numeral (e.g., CCLV or MMXXVI) directly into the Roman Numeral field, and the Decimal, Binary, Octal, and Hexadecimal values will calculate instantly.

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