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Free online number base converter

A number base converter translates integers between positional numeral systems. Type a value in one base and see the equivalent in binary, octal, decimal, and hexadecimal — all at.

About this calculator

How to use

  1. Type the number to convert in the Value field.
  2. Set From base to the current base of your number.
  3. Set To base to the target base.
  4. Results update automatically — no button needed.

Formulas

To parse a value in base b:

decimal = sum of (digit × b^position) for each digit, right to left

To express a decimal integer n in base b:

repeatedly divide n by b, collecting remainders right-to-left

Worked example

Convert 255 (decimal) to hexadecimal:

255 ÷ 16 = 15 remainder 15 → F
15  ÷ 16 = 0  remainder 15 → F
Read remainders right-to-left → FF

Convert FF (hex) to binary:

F = 1111 in binary
FF = 11111111 in binary (8 bits)

Standard representations

DecimalBinaryOctalHex
0000
10101012A
16100002010
25511111111377FF
256100000000400100

Frequently asked

What is a number base?
A number base (or radix) is the number of unique digits a positional numeral system uses. Decimal uses 10 digits (0–9), binary uses 2 (0–1), hexadecimal uses 16 (0–9 and A–F).
How does base conversion work?
Every integer can be expressed in any base. To convert, first interpret the input number in its original base (parsing each digit by its positional weight), then express the resulting integer in the target base using repeated division or the digits of that base.
Why is hexadecimal used in computing?
One hex digit represents exactly four binary bits, so a byte (8 bits) maps cleanly to two hex digits. This makes memory addresses, color codes, and binary data far more readable than a long string of 0s and 1s.
What characters are valid in each base?
Base 2 uses 0–1; base 8 uses 0–7; base 10 uses 0–9; base 16 uses 0–9 and A–F. For bases above 10, letters continue: base 36 uses 0–9 and A–Z.
Does this support negative numbers?
Not currently. The converter works with non-negative integers only.
How do I share a conversion?
Click Share with my numbers to copy a URL that pre-fills your value and base selections for anyone you send it to.

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