Binary converters
Decimal to binary converter.
Decimal 10 is binary 1010, 100 is 1100100 and 255 is 11111111. Output is padded to whole 4-bit groups.
Input
Result
Enter a decimal number.
How to decimal to binary by hand
Divide the number by 2 and write down the remainder. Keep dividing the quotient by 2 until you reach 0, then read the remainders from last to first.
For 10: 10 / 2 = 5 remainder 0; 5 / 2 = 2 remainder 1; 2 / 2 = 1 remainder 0; 1 / 2 = 0 remainder 1. Reading upward gives 1010.
Worked examples
| Decimal | Binary |
|---|---|
| 10 | 1010 |
| 65 | 0100 0001 |
| 100 | 0110 0100 |
| 255 | 1111 1111 |
| 1024 | 0100 0000 0000 |
Need text, decimal and hex side by side? Use the full binary converter, or look a character up in the ASCII table.
Decimal to binary FAQ
How do you convert decimal to binary?
Divide by 2 repeatedly and record each remainder, then read the remainders from the last one back to the first. 10 gives 1010.
What is 255 in binary?
11111111, eight 1 bits. It is the largest number that fits in one unsigned byte.
What is 100 in binary?
1100100, which is 64 + 32 + 4. The converter shows it padded to 0110 0100.
How are negative numbers shown?
With a minus sign in front of the magnitude, for example -5 is -0101. Computers store negatives as two's complement at a fixed width, which is a different representation; use the two's complement calculator for that.