Decimal to Binary Converter
Convert decimal numbers to binary (base 2), with optional 4- or 8-bit digit grouping. Handles huge and negative numbers.
Runs in your browserDecimal → Binary
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Example
42 255
101010 11111111
How to use the Decimal to Binary Converter
- Enter one number per line to convert several at once. Negative numbers and numbers of any size are supported.
Privacy and limitations
- Your data is processed on your device and is not uploaded to any server.
- Whole numbers only; fractional parts (e.g. 10.5) are not converted.
- Negative numbers are written with a minus sign; use the two’s complement converter for fixed-width bit patterns.
Frequently asked questions
How do you convert decimal to binary by hand?
Divide by 2 repeatedly and write down the remainders; reading them from last to first gives the binary digits. 42 → 0,1,0,1,0,1 → 101010.
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