Number Base Converter

Convert Numbers Between Binary, Hex, Decimal, and Any Base

Type a whole number in any base — binary, octal, decimal, hexadecimal, or a custom base from 2 to 36 — and every other field updates at the same time. There's no convert button and no page reload: edit one field, read the rest.

It uses arbitrary-precision integers, so it converts numbers far larger than a 64-bit register can hold. A 128-bit token or a 500-digit value converts exactly, with no rounding, overflow, or scientific-notation surprises. Paste with the usual separators (spaces, underscores, commas) or a leading 0x, 0b, or 0o and it still reads correctly.

Invalid digits are caught per field — if you drop a "2" into the binary box or a "g" into the hex box, that field tells you exactly which character doesn't belong, instead of silently giving a wrong answer.

• Programming: Read a hex color, memory address, or bitmask as decimal and flip it straight back to hex or binary.
• Unix permissions: Turn a chmod value like 755 between octal and its underlying bit pattern.
• Networking: Convert an IP octet or subnet value between decimal and binary to reason about masks.
• Learning and homework: Check base-conversion exercises in binary, octal, and hex all at once and see the digit count and bit length.
• Big identifiers: Convert 128-bit tokens, hashes, or database IDs without hitting floating-point limits.
• Custom encodings: Work in base 32, base 36, or any base down to 2 for URL-safe IDs and encoding schemes.

Privacy: This tool runs entirely in your browser. Nothing you type is uploaded, logged, or sent anywhere — the conversion math happens on your own device.