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ToolWrenConvert a number between binary, octal, decimal and hexadecimal. Enter a value, pick its base, and see all four at once.
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Number Base is a free, private online tool that lets you convert numbers between binary, octal, decimal and hexadecimal instantly. It runs entirely in your browser, so nothing you enter is uploaded to a server.
Privacy: this tool runs entirely in your browser. Your input is never sent to, received by, or stored on any server — there are no uploads and no tracking of what you enter.
Binary (base 2) uses 0-1, octal (base 8) uses 0-7, decimal (base 10) is everyday numbers, and hexadecimal (base 16) uses 0-9 and A-F. Programmers switch between them constantly.
Hex is a compact way to write binary — each hex digit is exactly 4 bits. Colors, memory addresses and byte values are usually shown in hex.
Type your number, choose the base it is currently in, and the tool shows the binary, octal, decimal and hex equivalents.
A number base (or radix) is how many distinct digits a system uses. We count in base 10 (decimal, digits 0–9), but computers work in base 2 (binary, 0–1), and programmers frequently use base 8 (octal) and base 16 (hexadecimal, 0–9 then A–F). This converter shows a whole number in all four at once.
Each digit's value depends on its position and the base: in decimal, 255 is 2×100 + 5×10 + 5×1; in hex the same value is FF (15×16 + 15). The tool reads your number in its stated base, computes the underlying integer, then re-expresses that integer in binary, octal, decimal and hexadecimal. The number itself never changes — only how it is written.
Hex is popular with programmers because it maps perfectly onto binary: each hex digit is exactly four bits, so a byte is two hex digits. That makes long binary numbers compact and readable. Colours (#FF8800), memory addresses, byte values and Unicode code points are all conventionally written in hex for this reason.
Octal (base 8) groups bits in threes and was common in early computing. Today its most visible use is Unix file permissions — chmod 755 uses octal digits to set read/write/execute bits. Seeing a value in octal alongside the other bases helps when working with permissions or legacy systems.
Convert between bases for low-level programming, debugging, colour codes, file permissions and computer-science study. This tool focuses on non-negative whole numbers; for converting text or raw bytes to and from hex or binary, use the dedicated Hex and Binary tools. Everything runs in your browser.