Decimal to Binary Converter
Enter a normal number and get its binary form straight away. Change the target base if you need octal or hex.
Be the first to rate this tool
The formula
Divide by 2 repeatedly and read the remainders from bottom to top.
The divide-by-two method
Divide the number by 2 and write down the remainder. Divide the result by 2 again and repeat until you reach 0. The binary number is the remainders read from the last to the first.
For 13: 13 / 2 = 6 remainder 1, 6 / 2 = 3 remainder 0, 3 / 2 = 1 remainder 1, 1 / 2 = 0 remainder 1. Reading upwards gives 1101.
Quick reference
| Decimal | Binary |
|---|---|
| 1 | 1 |
| 2 | 10 |
| 5 | 101 |
| 10 | 1010 |
| 64 | 1000000 |
| 255 | 11111111 |
Examples to check
Type these into the calculator above to see how it behaves. Every result below was produced by the same calculator code that runs on this page.
| What you enter | What you get |
|---|---|
| Value: 13; Decimal (10); Binary (2) | Base 2: 1101 |
| Value: 255; Decimal (10); Binary (2) | Base 2: 11111111 |
| Value: 64; Decimal (10); Binary (2) | Base 2: 1000000 |
| Value: 1000; Decimal (10); Binary (2) | Base 2: 1111101000 |
Decimal to Binary Converter: frequently asked questions
Can it convert negative numbers?
Yes, it shows the binary of the size of the number with a minus sign. It does not show two's complement, which depends on how many bits you choose.
Can I convert decimals like 0.5?
This tool converts whole numbers only.
Does the conversion happen on my device?
Yes. Your text, colours and files are processed in your browser and never uploaded.
Is what I enter in this converter saved or sent anywhere?
No. The calculation runs in your browser, so what you enter is not sent to our servers. We only count, anonymously, whether a tool ran successfully.
Is this converter free to use?
Yes. It is free, needs no sign-up and has no usage limit.
Last reviewed: October 3, 2026