Number Base Converter
Convert numbers instantly between binary, octal, decimal, and hexadecimal. One input updates all four representations at once, the fastest way to see 255 as FF and 11111111 together.
Using the Number Base Converter: step by step
- Type a number in any of the four base fields.
- The other three representations update immediately.
- Or type a value with a prefix like 0x1F or 0b101 to have the base detected.
- Copy whichever representation you need.
What people use the Number Base Converter for
- Converting hex color codes and memory addresses to decimal.
- Checking binary representations while learning bitwise operations.
- Reading octal file permissions in Unix-style systems.
- Translating values between documentation written in different bases.
Inside the Number Base Converter
The converter parses each field according to its base, radix 2, 8, 10, or 16, and re-renders the value in all four. Prefix notation such as 0x for hexadecimal and 0b for binary is recognized, matching how literals appear in most programming languages. Negative numbers are supported, and all conversions are computed locally as you type.
Limitations worth knowing
Conversions use standard integer arithmetic; fractional values and very large numbers beyond JavaScript's safe integer range are not supported.
Number Base Converter FAQ
What does 0x mean?
It is the conventional prefix marking a hexadecimal literal, used across C-family languages.
Can it convert negative numbers?
Yes, signed values convert with a leading minus sign in each base.
Why do programmers use hexadecimal?
Each hex digit maps cleanly to four binary digits, making it a compact shorthand for binary data.
Last reviewed: October 2026.