70 toolsAbout Number Base Converter
Convert any whole number between binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16) instantly. Type a value in any one base and see the equivalent in all four bases update immediately, along with a visual bit breakdown showing exactly which binary digits are set.
Number base conversion is a core skill in computer science and programming. Binary is how computers represent data at the hardware level, hexadecimal is the standard for memory addresses, color codes, and byte values, and octal still appears in Unix file permissions (like chmod 755) and some legacy systems. Decimal is how humans normally read and write numbers.
This tool supports custom bases too, so you can convert into or out of any base from 2 to 36 — useful for working with base36 short URLs, custom encoding schemes, or computer science coursework.
Click any result to instantly set it as the new input value, copy any result with one click, and use the bit-by-bit breakdown to understand exactly how a number is represented at the binary level — handy for learning bitwise operations, flags, and masks.
Everything runs locally in your browser using standard JavaScript number parsing. Your numbers are never uploaded or transmitted anywhere.
How to Use Number Base Converter
Type a number into the input field.
Choose which base that number is currently in: binary, octal, decimal, hexadecimal, or any custom base from 2–36.
See the equivalent value in every other base update instantly, along with a bit-by-bit binary breakdown.
Click any result row to use it as the new input, or copy any value with one click.
Examples
Frequently Asked Questions
What number bases are supported?
Binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16) are shown by default, plus a custom base selector supporting any base from 2 to 36.
Can I convert negative numbers?
Yes — enter a negative decimal number (e.g. -42) and it converts correctly across all bases. Binary, octal, and hex results show the negative sign rather than two's complement representation.
Does this support decimal (fractional) values?
This tool converts whole integers only. Fractional values are truncated to the integer part, since binary/octal/hex representations of fractions aren't a single standard format.
What's the largest number this can convert?
Values are handled as standard JavaScript numbers, which are precise up to 2^53 (about 9 quadrillion) before precision is lost. That covers the vast majority of programming and computer science use cases.
How does hexadecimal relate to binary?
Each hexadecimal digit represents exactly 4 binary bits, since 16 = 2^4. That's why hex is commonly used as a compact, human-readable shorthand for binary data — for example, the byte 11110000 in binary is simply F0 in hex.
Why is octal still used today?
Octal remains common in Unix and Linux file permissions. A permission like 755 (rwxr-xr-x) is an octal number where each digit represents 3 bits — read, write, and execute — for owner, group, and others.
Can I use this for base36 or custom bases?
Yes — select 'Custom' and enter any base from 2 to 36. Base 36 uses digits 0-9 and letters a-z, and is commonly used for compact ID encoding and short URLs.