Dev Tool

Number Base Converter

Convert numbers between binary, octal, decimal and hexadecimal instantly. Edit any field to update all others.

Binary (Base 2)

Octal (Base 8)

0-7

Decimal (Base 10)

0-9

Hexadecimal (Base 16)

0-9, A-F

BIT VISUALISATION

CUSTOM BASE CONVERTER

Number

From base

To base

Result

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Edit any field

Change any value and all other bases update instantly. No convert button needed.

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Bit visualiser

See the binary representation of any number as individual bits with position labels.

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Custom bases

Convert between any base from 2 to 36 — including base 32, base 58 and others.

Frequently Asked Questions

What number bases does the converter support?

The converter supports the four most common bases used in computing: binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16). Enter a value in any base and the tool instantly shows the equivalent in all other bases.

Why are hexadecimal numbers used in computing?

Hexadecimal is used because it maps neatly to binary — each hex digit represents exactly four binary bits. This makes it much more compact and readable than raw binary for memory addresses, color codes, byte values, and machine code.

Can I convert negative numbers?

The converter handles positive integers. For negative numbers in binary, you would need to work with two's complement representation, which is the convention used by most processors. Enter the magnitude and apply two's complement rules manually if needed.

What are number bases used for in programming?

Binary (base 2) is the fundamental language of computers — all data is stored as 0s and 1s. Hexadecimal (base 16) is used to represent binary data compactly — memory addresses, color codes (#FF5733), byte values. Octal (base 8) is used in Unix file permissions (chmod 755).

How do I convert binary to decimal manually?

Multiply each bit by 2 raised to its position (counting from 0 on the right). 1011 in binary = 1×8 + 0×4 + 1×2 + 1×1 = 8+0+2+1 = 11 in decimal.

What is the maximum number I can convert?

JavaScript handles integers safely up to 2^53 - 1 (9,007,199,254,740,991). For larger numbers the converter uses BigInt internally where supported.

Number bases in everyday computing

A number base is how many digits a counting system uses. People count in base 10, while computers work in base 2. This converter translates between binary, octal, decimal and hexadecimal, shows the bits visually and supports custom bases up to 36.

Binary (base 2) uses 0 and 1. Network masks and permission flags are easiest to understand in binary.
Octal (base 8) appears in Unix file permissions: chmod 755 means read, write and execute for the owner, and read and execute for everyone else.
Hexadecimal (base 16) uses 0 to 9 and A to F. Colours like #FF8800, MAC addresses and hashes are written in hex because each hex digit is exactly four bits.
Base 36 uses 0 to 9 and A to Z, which makes compact codes for short links.

Worked example

Decimal 200 is 11001000 in binary, 310 in octal and C8 in hexadecimal. Reading binary from the right, the positions stand for 1, 2, 4, 8, 16, 32, 64 and 128, and here 128 + 64 + 8 = 200.

Common mix-ups

Prefixes. Code marks bases with 0b for binary, 0o for octal and 0x for hex. In some languages a plain leading zero also means octal, which can silently change a number.
Signed numbers. Negative values are stored in two's complement, so 11111111 is 255 as an unsigned byte but -1 as a signed one.
Subnet masks. 255.255.255.0 is 24 ones in binary, which is why it is written /24. The CIDR calculator works out the rest.