Number Base Converter
Type a number in any base and read it in binary, octal, decimal and hexadecimal at the same time. Values are handled as big integers, so long numbers keep every digit.
Free Runs locally No signup
Binary
11111111Octal
377Decimal
255Hexadecimal
FFSpaces and underscores are ignored; 0b, 0o and 0x prefixes are supported.
How to use it
1
Select the input base
Choose binary, octal, decimal or hexadecimal for the value you want to enter.
2
Type a value
Paste digits, spaces or a 0b / 0o / 0x prefix; the other bases update immediately.
3
Copy a result
Copy any of the four representations with its own button.
Why use this tool
Four bases at once
Binary, octal, decimal and hexadecimal results are shown side by side.
Big integers
Values are converted with BigInt, so 100-digit numbers stay exact.
Prefix aware
0b, 0o and 0x prefixes are understood, and spaces or underscores are ignored.
Frequently asked questions
Are negative numbers supported?
This converter works with unsigned values. For signed representations, convert the absolute value and apply two’s complement yourself.
How long can the input be?
Up to 200 characters after spaces and underscores are removed. That is far beyond the range of 64-bit integers and covers most practical conversions.
Are leading zeros kept?
No. Numeric values drop leading zeros, so 0001 in binary is shown as 1. This keeps the four representations consistent.
Why is my input marked invalid?
Each base accepts a fixed set of digits: 0–1 for binary, 0–7 for octal, 0–9 for decimal and 0–9 plus A–F for hexadecimal.
Is the conversion done locally?
Yes. Everything runs in your browser and no value is sent to a server.
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