H1_Number Base Converter - Binary, Octal, Decimal, Hex | MultiTool

How it works

Type a number, choose the base it is written in, and instantly see its value in binary, octal, decimal and hexadecimal. Invalid digits for the source base are rejected automatically.

Binary, hex and the bases that run the world

A number base is just how many symbols you count with before “carrying” — decimal uses 10 (0–9), binary uses 2 (0–1), hexadecimal uses 16 (0–9 plus A–F). The value is the same; only the notation changes.

• Why binary exists: transistors have two reliable states — on/off. Everything digital is bits at the bottom: 8 bits = 1 byte = values 0–255.
• Why hex is everywhere: one hex digit maps exactly to 4 bits, so a byte is always two tidy characters. Colors (#ff5f1f), MAC addresses, memory dumps and error codes all speak hex.
• Octal (base 8) survives in file permissions on Unix systems — that curious chmod 755 is octal.
• The positional trick: 1011 in binary is 1×8 + 0×4 + 1×2 + 1×1 = 11. Every base works this way — the converter just does it instantly, any direction, with full precision up to 64-bit values.

Your privacy

Everything runs entirely in your browser. Nothing you type is ever sent to any server or stored.