Number Base Converter
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Convert numbers between binary, octal, decimal, hexadecimal and any base from 2 to 36.
Type a number in any box — the others update instantly.
About this tool
This tool converts whole numbers between binary (base 2), octal (base 8), decimal (base 10), hexadecimal (base 16) and any other base up to 36. Type in any box and all the others update instantly. It handles numbers of any size exactly — even hundreds of digits — and negative numbers too.
How to use
- Type a number in the box for the base it is written in — for example 255 in Decimal, or FF in Hexadecimal.
- Every other base updates as you type. Choose a custom base (2–36) for the last box.
- Tick "Group digits" to make long numbers easier to read, then copy any result.
FAQ
How do I convert binary to decimal by hand?
Multiply each digit by 2 to the power of its position, counting from 0 on the right, and add them up. For 1011: 1×8 + 0×4 + 1×2 + 1×1 = 11.
What are 0x, 0b and 0o?
Prefixes used in programming to show the base: 0x for hexadecimal (0xFF), 0b for binary (0b1010) and 0o for octal (0o17). You can paste numbers with these prefixes — they are ignored.
Which digits are used above base 10?
Letters: A = 10, B = 11 … F = 15 in hexadecimal, up to Z = 35 in base 36. Upper and lower case letters are read the same way.
Is there a size limit?
No practical limit. The tool uses JavaScript’s BigInt, so very large numbers convert exactly, without rounding.