BYTETOOLS

Number Base Converter

Convert whole numbers between any bases from 2 to 36, with from-base and to-base selectors and digit validation. Free online number base converter.

255
Decimal value

Result in base 2

11111111

  • Converts between any bases from 2 to 36
  • Separate from-base and to-base selectors
  • Exact BigInt maths for very large numbers
  • Validates digits against the chosen base
  • Shows the decimal value for reference
  • Private, client-side conversion

How to use the Number Base Converter

  1. 1

    Choose the base your number is currently written in.

  2. 2

    Choose the base you want to convert it to.

  3. 3

    Type the number using valid digits for the from-base.

  4. 4

    Read the converted value and its decimal equivalent.

  5. 5

    Copy the result to your clipboard.

About the Number Base Converter

The ByteTools Number Base Converter changes an integer from one numeral base to another, supporting every base from 2 (binary) to 36. Pick a from-base and a to-base, type your number, and the converted value appears instantly along with its decimal equivalent.

Programmers use it for binary, octal, hexadecimal and beyond, while students explore how positional number systems work. Bases above 10 use letters as extra digits — a to z — exactly like hexadecimal extends 0–9 with A–F.

Conversion runs locally in your browser using exact BigInt arithmetic, so even very long numbers stay accurate. Digits are validated against the chosen base, and nothing you enter is uploaded or stored.

Frequently asked questions

What bases can this converter handle?

It handles every base from 2 to 36. Base 2 is binary, base 8 is octal, base 16 is hexadecimal, and higher bases use the letters a through z as digits, giving 36 possible symbols in total (0–9 and a–z).

How do you convert binary to decimal?

Each binary digit represents a power of two, doubling from right to left. Set the from-base to 2 and the to-base to 10, type your binary number, and the converter sums the place values to give the decimal result.

Why are letters used as digits in higher bases?

Once a base exceeds 10, single digits run out, so letters fill in. Hexadecimal uses A–F for 10–15, and base 36 goes all the way to Z for 35. This keeps each digit a single character regardless of the base.

What does 'invalid digit' mean?

It means a character in your number is not allowed in the chosen from-base — for example the digit 2 in a binary number, or the letter G in hexadecimal. The converter lists the valid digits so you can correct the input.

Can it convert very large numbers?

Yes. The tool uses BigInt, so it converts numbers of any length exactly without rounding. This makes it reliable for long binary strings or large hexadecimal values that would overflow an ordinary calculator.

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