Last updated: 2026-06-19
Decimal to Binary Converter
Turn any whole number into base-2 bits instantly.
A decimal to binary converter rewrites a base-10 number using only the digits 0 and 1. Binary is how computers store every value, with each bit standing for a power of two. Type a decimal number below and read its binary equivalent, or use the reverse tool to go from binary back to decimal.
How to convert decimal to binary
- Type or paste your decimal (base-10) number into the Decimal field.
- Read the binary result, made up only of 0s and 1s, in the Result field.
- Use the copy button to grab the bit string.
Worked example: 13 in binary
Break 13 into powers of two: 8 + 4 + 1 = 13, while 2 is left out. Marking each power present (1) or absent (0) from 8 down to 1 gives 1101. You can check it: 1×8 + 1×4 + 0×2 + 1×1 = 13.
Reference table
| Decimal | Hex | Binary |
|---|---|---|
| 0 | 0 | 0 |
| 1 | 1 | 1 |
| 2 | 2 | 10 |
| 3 | 3 | 11 |
| 4 | 4 | 100 |
| 5 | 5 | 101 |
| 8 | 8 | 1000 |
| 10 | a | 1010 |
| 13 | d | 1101 |
| 16 | 10 | 10000 |
| 32 | 20 | 100000 |
| 64 | 40 | 1000000 |
| 100 | 64 | 1100100 |
| 128 | 80 | 10000000 |
| 255 | ff | 11111111 |
| 256 | 100 | 100000000 |
Convert binary to decimal
Already have a binary value? Use the reverse converter to read it back as a base-10 number.
Frequently asked questions
- How do I convert decimal to binary by hand?
- Divide the number by 2 repeatedly and write down each remainder (0 or 1). Reading the remainders from last to first gives the binary value. This tool performs the same steps instantly.
- What is 10 in binary?
- The decimal number 10 is 1010 in binary: that is one 8, no 4, one 2, and no 1 (8 + 2 = 10).
- How many bits do I need for a number?
- A value fits in n bits when it is below 2 to the power n. For example 255 needs 8 bits because it is one less than 256 (2^8).
- Why does this converter only show positive binary?
- It outputs the plain magnitude in unsigned binary. Negative or fractional inputs are clamped or rejected, since two’s-complement width depends on the data type you choose.