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Decimal to Binary Converter

Need the binary form of a decimal number for bit masks, flags, or low-level debugging? Type the base-10 value and read off its 0s and 1s. Everything runs locally in your browser.

=
11111111

Decimal (base 10) in, Binary (base 2) out.

How it works

Repeatedly divide by 2 and read the remainders bottom-to-top. 13 → 6 r1, 3 r0, 1 r1, 0 r1 → 1101.

Examples

FAQ

How do I convert decimal to binary?

Repeatedly divide by 2 and read the remainders bottom-to-top. 13 → 6 r1, 3 r0, 1 r1, 0 r1 → 1101. Or just paste your decimal value into the box above and the binary result appears instantly.

Does this Decimal to Binary converter run in my browser?

Yes. The conversion happens entirely client-side — nothing you type is uploaded — and it uses big-integer math, so even very long decimal numbers convert exactly.

What is the largest number I can convert?

There is no practical limit. Because the converter works with arbitrary-precision integers, a decimal value of any length converts without rounding or overflow.

Need other bases, custom radixes, or two-way editing? Use the full Number Base Converter.

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