Number Base Converter
Number
Common values
Type a number in any field — all bases update live. Supports negative integers and arbitrarily large values.
Why use a private number base converter?
Developers constantly move between number bases — hex memory addresses in debuggers, binary register values in embedded systems, octal Unix file permissions, decimal port numbers. Mental arithmetic between bases is error-prone and slow. A dedicated converter eliminates that friction and reduces transcription mistakes.
Most online converters require a form submission or show ads. This one updates all four bases simultaneously as you type, runs entirely in your browser, and handles integers of any size — including the large values that appear in networking and cryptography.
How it works
Type a value in any of the four fields — binary, octal, decimal, or hexadecimal — and the converter immediately parses it as a JavaScript BigInt and recomputes all other representations. BigInt has no upper size limit, so there are no overflow issues with large values like 64-bit integers or cryptographic constants.
Negative numbers are supported in all bases. The Copy button on each row includes the conventional prefix — 0x for hex, 0o for octal — so you can paste directly into code.
Common use cases
- Reading hex memory addresses in a debugger and converting to decimal for arithmetic
- Checking Unix file permission bits — e.g. confirming 755 in octal is 111 101 101 in binary
- Working with IPv4 subnet masks like 255.255.255.0 and understanding their binary structure
- Converting RGB color channel values between decimal and hex for CSS or design tools
- Inspecting 16-bit or 32-bit register values in embedded systems or microcontroller datasheets
- Understanding port number limits — 65535 is 0xFFFF, the maximum for a 16-bit unsigned integer
- Verifying bit flag values in low-level protocol implementations or network packet analysis
Frequently asked questions
- Which number bases are supported?
- Binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16). Type a value in any field and all others update instantly — no submit button needed.
- What do the 0x and 0o prefixes mean?
- 0x is the conventional prefix for hexadecimal values used in C, JavaScript, Python, and most other languages. 0o is the octal prefix used in Python 3 and modern JavaScript. The Copy button on each row includes the prefix so you can paste directly into code.
- Does it support large numbers?
- Yes. The converter uses JavaScript BigInt internally, so there is no practical upper limit. It correctly handles 64-bit integers, cryptographic constants, and other values that overflow standard 32-bit or 53-bit representations.
- Are negative numbers supported?
- Yes. Prefix any value with a minus sign and the converter handles it correctly across all four bases.
- Why are values like 255, 65535, and 4294967295 listed as presets?
- 255 (0xFF) is the maximum 8-bit unsigned integer — the upper limit for a single byte, common in RGB color values and networking. 65535 (0xFFFF) is the maximum 16-bit value and the highest valid network port number. 4294967295 (0xFFFFFFFF) is the maximum 32-bit unsigned integer, which appears in IPv4 address arithmetic and 32-bit register values.