Number Base Converter

How to use Number Base Converter

1. 1

   Pick a field

   Choose the base you already have your number in — Decimal, Binary, Octal or Hexadecimal. There’s a labelled field for each.

2. 2

   Type your number

   Enter a whole, non-negative number. As you type, the other three fields update live with the equivalent value — no convert button needed.

3. 3

   Read the conversions

   The remaining fields show the same value in every other base at once. Hexadecimal is shown in uppercase by convention.

4. 4

   Fix any invalid input

   If you enter a digit that isn’t valid for that base (for example a “2” in binary), an inline message points it out while the other fields keep their values.

Key features

• Convert between binary, octal, decimal and hexadecimal in one place
• Live, two-way conversion — edit any field and the rest update instantly
• Per-base validation with friendly inline errors that don’t clear other fields
• Case-insensitive hexadecimal input; uppercase hex output
• BigInt-powered, so very large integers convert without losing precision
• Runs 100% in your browser — nothing uploaded, free with no sign-ups

Frequently asked questions

How do I convert binary to decimal?

Type your binary number (only 0s and 1s) into the Binary field. The Decimal field — along with Octal and Hexadecimal — updates instantly with the converted value. To go the other way, type into the Decimal field instead.

How do I convert decimal to hexadecimal?

Enter your number in the Decimal field and read the result from the Hexadecimal field. Hex output is shown in uppercase (for example 255 becomes FF). The same live update works for converting decimal to binary or octal too.

What is hexadecimal?

Hexadecimal is base 16: it uses the digits 0–9 plus the letters A–F (where A=10 through F=15). Because one hex digit maps neatly to four binary digits (bits), it’s a compact way to write binary values and is common in colour codes, memory addresses and byte values.

What is the difference between binary, octal, decimal and hex?

They’re the same numbers written in different bases. Binary is base 2 (digits 0–1), octal is base 8 (0–7), decimal is base 10 (0–9, what we use day to day), and hexadecimal is base 16 (0–9 and A–F). This tool converts a single value between all four at once.

Are large numbers supported, and why use BigInt?

Yes. The converter uses JavaScript’s BigInt, so integers larger than 2⁵³ − 1 (the point where regular numbers start losing precision) convert exactly. Functions like parseInt and Number would silently round huge values; BigInt keeps every digit correct.

Can it convert negative numbers or fractions?

No — this tool is designed for non-negative whole numbers only. Signs, decimal points and digit separators are treated as invalid input, and the affected field will show an inline error while the other fields keep their values.

Is my data sent to a server?

No. All parsing and conversion happens locally in your browser. Whatever you type never leaves your device, and the tool keeps working offline once the page has loaded.

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