Number base converter

Convert an integer between binary, octal, decimal and hexadecimal, see the 64-bit layout, the signed value at each width, and toggle individual bits. Runs entirely in your browser.

Enter an integer (0x / 0b / 0o prefixes auto-detected; underscores allowed)

Binary (64-bit, grouped by 4)—

Octal—

Decimal—

Hexadecimal—

Interpretation by width (signed)—

Edit bit by bit (click to toggle)

Computed locally in your browser — nothing is sent anywhere. · Try:

What this shows

Binary / octal / decimal / hex — the same value in every base, with 0x/0b/0o prefixes auto-detected.
Signed by width — how the bits read as int8/16/32/64 (two's complement), which is where most sign bugs come from.
Bit editor — click any of the 64 bits to flip it and watch the value change.

Related reading: undefined behaviour in C, and endianness in practice.