Binary, Hex, Decimal & Octal Converter (Free Online Tool)

Computers think in binary, humans think in decimal, and programmers live in hexadecimal. Converting a number between these bases by hand is slow and error-prone — one slipped digit and a color code, memory address, or permission flag is wrong. A base converter does it instantly. Here's how to use one and what each base is actually for.

The four bases, quickly

• Binary (base 2) — just 0 and 1. How computers store everything at the lowest level.
• Decimal (base 10) — the everyday numbers humans use.
• Hexadecimal (base 16) — 0–9 plus A–F. Compact and maps neatly to binary (one hex digit = four bits), which is why it's everywhere in programming: color codes (#FF8800), memory addresses, byte values.
• Octal (base 8) — 0–7. Less common now, but still used for Unix file permissions (chmod 755).

How to use the converter

The free converter handles all four:

1. Open it — no signup.
2. Enter a value in any base.
3. See it converted to the others instantly.

It runs in your browser — fast, offline-capable once loaded, nothing uploaded.

Where you'll reach for it

• Color codes — translating a hex color to RGB decimal values.
• Bit math and flags — reading a hex value as its binary bits.
• File permissions — decoding an octal chmod value.
• Debugging — making sense of a hex memory address or byte dump.
• Learning — seeing how the same number looks across bases.

A quick intuition

Hex is popular because it's a clean shorthand for binary: every hex digit is exactly four binary digits. So FF is 1111 1111 (255 in decimal). Once that clicks, a long binary string becomes a short, readable hex value — which is the whole reason programmers use it.

Common questions

Why do programmers use hexadecimal? It's compact and maps cleanly to binary (one hex digit = four bits), making byte values, colors, and addresses easy to read.

What's octal used for? Most commonly Unix/Linux file permissions, like chmod 644.

Is my input private? Yes — the converter runs entirely in your browser and uploads nothing.

Related reading: Base64 Encode & Decode · explore the other free tools.

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