Number Base Converter

Number bases are fundamental to computing — binary powers every logic gate in your CPU, hexadecimal makes binary readable for debugging memory dumps and color codes, octal survives in Unix file permissions, and decimal is how the rest of us think. Our free Number Base Converter gives you instant conversion between all four bases in a single view. Enter a number in any base — select binary, octal, decimal, or hex as the input format — and see all four representations simultaneously with one-click copy for each format. The step-by-step expansion shows exactly how each digit contributes to the decimal value, making it an excellent learning tool for computer science students and anyone who wants to understand how position-based number systems actually work.

How to Use the Converter

1. Enter a number — Type any number into the input field. Valid digits depend on the selected base: 0–1 for binary, 0–7 for octal, 0–9 for decimal, and 0–9/A–F for hexadecimal.
2. Select the input base — Choose Binary, Octal, Decimal, or Hex using the base selector buttons. The tool validates your input against the chosen base and shows an error for invalid digits.
3. Read all four representations — The results grid instantly shows your number in binary (with nibble grouping), octal, decimal (with thousands separators), and hex — all from a single input.
4. Copy any format — Each result card has a copy button to grab the raw value (without formatting) to your clipboard.

Key Features

• All Four Bases at Once

  See binary, octal, decimal, and hex simultaneously — no need to re-enter the number for each base.

• Input Validation

  Real-time validation prevents invalid digits for each base. Clear error messages explain what went wrong.

• Readable Formatting

  Binary grouped in nibbles (4 digits), hex in 4-digit groups, and decimal with thousands separators for readability.

• Step-by-Step Expansion

  See the positional notation breakdown — each digit multiplied by its place value — for educational clarity.

• One-Click Copy

  Copy raw values from any base format — formatted spacing is stripped so values paste cleanly into code.

• 100% Client-Side

  All conversions use JavaScript's native parseInt and toString. No server round-trips needed.

Frequently Asked Questions