Convert between binary, octal, decimal and hex
Pick the base your number is currently in, type it, and this tool instantly shows the same value in all four number systems - binary, octal, decimal and hexadecimal. Handy for programming, networking (subnet masks, MAC addresses), and computer science homework.
How to use it
- Choose the input base.
- Type a valid number in that base.
- Read the converted value in all four bases at once.
Why these bases matter
Decimal (base 10) is what people use day to day. Binary (base 2) is how computers store everything at the hardware level - only 0s and 1s. Hexadecimal (base 16) is a compact way to write binary values, since each hex digit represents exactly 4 bits, which is why colours, memory addresses and MAC addresses are usually written in hex. Octal (base 8) is less common today but still shows up in Unix file permissions (like chmod 755).
Large numbers, no precision loss
This converter uses arbitrary-precision integer math, so it stays accurate even for numbers far larger than the 32-bit or 53-bit limits that trip up ordinary calculators.
Common uses
- Converting Unix file permission numbers (octal) to understand what they mean
- Reading hexadecimal colour codes or memory addresses as decimal
- Computer science coursework and interview practice
- Working with binary data, flags and bitmasks
Frequently asked questions
Which bases are supported?
Binary (base 2), octal (base 8), decimal (base 10) and hexadecimal (base 16) - all shown simultaneously.
Is there a size limit?
It handles arbitrarily large integers using JavaScript's BigInt, well beyond normal 32-bit or 64-bit limits.
Does it support decimals or negative numbers?
No, this converter works with positive whole numbers only, which covers the vast majority of programming and networking use cases.
Is it free?
Yes, completely free with no signup.