Convert between binary, octal, decimal and hexadecimal — type in any box and the rest update.
🔒 This tool runs entirely in your browser. Nothing you enter or upload is sent to our servers.
How to use the Number Base Converter
- Type a number in the binary, octal, decimal or hex box.
- All other boxes update instantly. Use the custom base row for any base from 2 to 36.
- Supports big integers — no 32-bit or 64-bit limit.
About this tool
Computers store numbers in binary (base 2). Hexadecimal (base 16) is a compact way to write binary — each hex digit is exactly four bits — which is why it appears in colour codes, memory addresses and MAC addresses. Octal (base 8) groups bits in threes and is still used for Unix file permissions.
This converter uses arbitrary-precision integers, so very long values convert exactly.
Frequently asked questions
How do I convert binary to decimal by hand?
Multiply each bit by its power of two and add them up. 1011₂ = 1×8 + 0×4 + 1×2 + 1×1 = 11.
Why is hex used for colours?
A colour has three 8-bit channels (red, green, blue). Each 8-bit value fits neatly in two hex digits, giving codes like #FF8800.
Does it handle negative or fractional numbers?
Integers only. A leading minus sign is supported; fractions are not.