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Decimal to Binary Converter

Convert decimal (base-10) numbers to binary (base-2).

Try an example:
Binary (2)
11111111
Octal (8)
377
Decimal (10)
255
Hexadecimal (16)
ff

Converting Decimal to Binary

Converting a decimal number to binary expresses it using only 0s and 1s — the form computers actually store and process.

How to convert Decimal to Binary by hand

  1. Divide the decimal number by 2 and record the remainder (0 or 1).
  2. Divide the quotient by 2 again, recording the remainder.
  3. Repeat until the quotient reaches 0.
  4. Read the remainders from bottom to top — that is the binary value.

Worked example

13 (decimal) → 1101 (binary) — 13 = 8 + 4 + 1, so the bits are 1101.

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Frequently asked questions

How do I convert Decimal to Binary?

Divide the decimal number by 2 and record the remainder (0 or 1). Divide the quotient by 2 again, recording the remainder. Repeat until the quotient reaches 0. Read the remainders from bottom to top — that is the binary value. Or just use the converter on this page — it does it instantly. Example: 13 (decimal) becomes 1101 (binary).

What is 13 (decimal) in binary?

13 (decimal) converts to 1101 (binary). 13 = 8 + 4 + 1, so the bits are 1101.

Is this converter free and private?

Yes — it is free and unlimited, and the conversion runs entirely in your browser, so nothing is uploaded to a server.