Free Number Base Converter
The Number Base Converter switches between binary, octal, decimal, hexadecimal, and any base from 2 to 36. Type a value in one base and the others update instantly.
For text rather than numbers, Text to Binary and ASCII to Hex show the same values written in other bases.
How to use the Number Base
- 1 Enter a number and choose its current base — binary, octal, decimal or hexadecimal.
- 2 Every other base is converted at once, so you can read them side by side.
- 3 Check the bit-group view, which spaces the binary into nibbles or bytes for easier reading.
- 4 Copy whichever representation you need.
How to Use
Enter a value and pick its base. Binary, octal, decimal, and hex all update live, and you can set a custom base (2–36) too.
- Binary, octal, decimal, hexadecimal
- Custom base 2–36
- Live sync across all fields
Frequently asked questions
Why do programmers use hexadecimal?
One hex digit maps to exactly four bits, so a byte is always two hex characters. Binary is unreadable at length and decimal does not align to byte boundaries, which makes hex the compact middle ground for memory addresses and colour codes.
How do I read a negative binary number?
Most systems use two’s complement: the most significant bit acts as a sign, and you invert every bit then add one to get the magnitude. So an 8-bit 11111111 is -1, not 255.
What is the largest number I can convert?
Values up to the safe integer limit of JavaScript, about 9 quadrillion, convert exactly. Beyond that, floating-point precision would silently round your number, so very large values need a big-integer approach.
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