Number Base Converter (Binary, Hex, Decimal)
Convert numbers between binary, octal, decimal, hexadecimal and any base 2–36 — 100% in your browser.
About Number Base Converter (Binary, Hex, Decimal)
Enter a number and see it instantly in binary, octal, decimal and hexadecimal, plus any custom base from 2 to 36. The base is detected automatically from 0x, 0b and 0o prefixes, or you can set it explicitly, and underscores are allowed as digit separators.
Conversions use arbitrary-precision BigInt math, so very large values stay exact — no floating-point rounding. Everything runs locally in your browser; nothing is uploaded.
Decimal to hex and binary
255
binary 11111111 · octal 377 · hex ff
Prefix with 0x, 0b or 0o and the input base is detected automatically.
Frequently asked questions
Which bases are supported?
Binary (2), octal (8), decimal (10) and hexadecimal (16) are always shown, plus any custom base from 2 to 36.
Does it handle very large numbers?
Yes. It uses BigInt arbitrary-precision arithmetic, so large values convert exactly without floating-point errors.
How does auto-detect work?
A 0x prefix is read as hexadecimal, 0b as binary and 0o as octal; anything else is treated as decimal. You can also pick the input base manually.
Is my data uploaded anywhere?
No. All conversion happens locally in your browser.