Number Base Converter
Free number base converter. Convert any value between binary (base 2), octal (base 8), decimal (base 10) and hexadecimal (base 16) instantly, with digit validation.
Input
Decimal Value
10
All Bases
How It Works
Choose the input base
Select whether your value is binary, octal, decimal or hexadecimal.
Type your value
Enter the number using only the digits valid for that base — for hexadecimal you can use 0-9 and A-F.
Read every base
The value is shown instantly in binary, octal, decimal and hexadecimal side by side.
Computers store everything as binary — strings of ones and zeros — but binary is hard for people to read, so programmers also use octal and especially hexadecimal as compact shorthand. Being able to move a value between binary, octal, decimal and hexadecimal is a core skill for anyone working with memory addresses, color codes, bit flags or low-level data.
This converter takes a value in any of the four common bases, validates that each digit is legal for that base, and then displays the equivalent value in all four representations at once. Hexadecimal output is shown in uppercase, the conventional form for color codes and memory dumps, so you can copy results straight into code.
Frequently Asked Questions
What is a number base?
A number base (or radix) is how many distinct digits a system uses. Decimal (base 10) uses 0-9, binary (base 2) uses 0 and 1, octal (base 8) uses 0-7, and hexadecimal (base 16) uses 0-9 plus A-F. The same quantity can be written in any base.
How do I convert binary to decimal?
Each binary digit represents a power of two. Reading right to left, multiply each digit by 2 raised to its position and add the results. For example 1010 = 1·8 + 0·4 + 1·2 + 0·1 = 10 in decimal. This converter does it for you instantly.
Why are letters used in hexadecimal?
Hexadecimal needs sixteen digit symbols, but we only have ten numerals (0-9). The letters A through F stand in for the values 10 through 15, so a single hex digit can represent any value from 0 to 15 — which maps neatly onto four binary bits.
What happens if I enter an invalid digit?
The converter validates your input against the digits allowed for the chosen base. If you type a digit that is not legal — such as a 2 in a binary number or a G in hex — it shows an error instead of an incorrect result.
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