Reading a hex value from a debugger, stack trace, or network packet and converting it to decimal to understand its magnitude or identify it as a known error code. Converting between CSS colour codes (e.g. #ff8800 or 0xff8800 ) and RGB triplets, or vice versa. Inspecting a bitmask or flags integer in binary to see which individual bits are set, or constructing a bitmask from a set of bit positions. Translating between base-36 shortened IDs (like URL slugs or API tokens) and their underlying decimal counters. Working with memory addresses, pointers, or offsets displayed in hex and needing to verify them in decimal. Converting between different data encodings — base-16 for byte streams, base-2 for bit-level operations, base-8 for legacy Unix permissions.

Enter a number in any supported base. Type a decimal integer, a hex string with 0x prefix, binary with 0b , octal with 0o , or any base-2 through base-36 value. Underscores can be used for digit grouping ( 1_000_000 ) and are automatically stripped. The tool parses and validates your input. It recognises common prefixes, handles both upper and lower case input, and rejects invalid digits for the chosen base. Conversion happens via BigInt internally. The input is parsed as a BigInt, then converted to every other base and displayed. This ensures perfect accuracy even for numbers larger than JavaScript's native Number type can handle. Results are shown in all common bases. You'll see decimal, binary, octal, hexadecimal, and base-36 side by side. Copy whichever format you need.

Negative numbers are sign-prefixed, not two's complement. -128 displays as -10000000 in binary, not as 10000000 . This matches how most languages handle arbitrary-precision integers; if you need fixed-width two's complement (e.g. for 8-bit or 16-bit values), interpret the output accordingly. Big numbers don't lose precision. JavaScript's native Number type only safely stores integers up to 2 53 − 1. This tool uses BigInt , so 64-bit integers, cryptographic hashes, and other large values round-trip exactly. Hex output is uppercase; base-32 and base-36 are lowercase. The tool normalises output for readability. If you need a specific case, adjust in your application code. Input is case-insensitive. Leading zeros are dropped. 0x000F becomes F . If you need fixed-width output (e.g. for byte pairs like FF 8B ), pad the result in your code after copying. Base-36 uses 0–9 and a–z. It's commonly used for compact representations of large integers and IDs, but isn't a standard encoding — always confirm the base with your data source.

Number Base Converter

Convert between binary, octal, decimal, hexadecimal, and any base from 2 to 36.

Input

From (base)

All bases

Base	Value
2 (binary)	`…`
8 (octal)	`…`
10 (decimal)	`…`
16 (hex)	`…`
32	`…`
36	`…`

What is this for?

Numbers are the same value regardless of which base you write them in — 255, 0xff, 0b11111111, and 0o377 all represent the same quantity. However, the base you work in matters enormously when you're debugging, reverse-engineering data layouts, reading memory dumps, or working with protocols and file formats. This tool converts between binary, octal, decimal, hexadecimal, and any arbitrary base from 2 to 36, using BigInt arithmetic to handle large integers without precision loss.

When to use it

Reading a hex value from a debugger, stack trace, or network packet and converting it to decimal to understand its magnitude or identify it as a known error code.
Converting between CSS colour codes (e.g. #ff8800 or 0xff8800) and RGB triplets, or vice versa.
Inspecting a bitmask or flags integer in binary to see which individual bits are set, or constructing a bitmask from a set of bit positions.
Translating between base-36 shortened IDs (like URL slugs or API tokens) and their underlying decimal counters.
Working with memory addresses, pointers, or offsets displayed in hex and needing to verify them in decimal.
Converting between different data encodings — base-16 for byte streams, base-2 for bit-level operations, base-8 for legacy Unix permissions.

How it works

Enter a number in any supported base. Type a decimal integer, a hex string with 0x prefix, binary with 0b, octal with 0o, or any base-2 through base-36 value. Underscores can be used for digit grouping (1_000_000) and are automatically stripped.
The tool parses and validates your input. It recognises common prefixes, handles both upper and lower case input, and rejects invalid digits for the chosen base.
Conversion happens via BigInt internally. The input is parsed as a BigInt, then converted to every other base and displayed. This ensures perfect accuracy even for numbers larger than JavaScript's native Number type can handle.
Results are shown in all common bases. You'll see decimal, binary, octal, hexadecimal, and base-36 side by side. Copy whichever format you need.

Common gotchas

Negative numbers are sign-prefixed, not two's complement. -128 displays as -10000000 in binary, not as 10000000. This matches how most languages handle arbitrary-precision integers; if you need fixed-width two's complement (e.g. for 8-bit or 16-bit values), interpret the output accordingly.
Big numbers don't lose precision. JavaScript's native Number type only safely stores integers up to 2⁵³ − 1. This tool uses BigInt, so 64-bit integers, cryptographic hashes, and other large values round-trip exactly.
Hex output is uppercase; base-32 and base-36 are lowercase. The tool normalises output for readability. If you need a specific case, adjust in your application code. Input is case-insensitive.
Leading zeros are dropped. 0x000F becomes F. If you need fixed-width output (e.g. for byte pairs like FF 8B), pad the result in your code after copying.
Base-36 uses 0–9 and a–z. It's commonly used for compact representations of large integers and IDs, but isn't a standard encoding — always confirm the base with your data source.