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Number Base Converter

Convert numbers between binary, octal, decimal, hexadecimal and any base from 2 to 36, with big-number and two's-complement support.

🔒 Runs in your browser — files never leave your deviceFree · No sign-up

0 uses the usual grouping for each base: 4 for binary, 3 for octal and decimal, 2 for hexadecimal. Grouping is applied to the boxes you are not typing in.

0Bits
0Bytes
+Sign

Two's complement

How this number is stored in a fixed-width integer. Negative values wrap around; values that are too large are flagged.

WidthBinaryHex

Try an example

How to use the base converter

  1. Type a number into any box — binary, octal, decimal, hexadecimal or your own base from 2 to 36 — and every other box updates instantly.
  2. Prefixes are understood, so 0xFF, 0b1010, 0o17, spaces and underscores can all be pasted straight in.
  3. Read the two's-complement table on the right to see how the value is stored as an 8, 16, 32 or 64-bit integer.

FAQ

How big a number can it handle?

Any whole number. Conversion uses JavaScript BigInt, so a 200-digit decimal or a 512-bit hex value converts exactly, with no floating-point rounding.

What does the two's-complement table show?

The bit pattern a CPU would actually store. -1 becomes FF in 8 bits and FFFFFFFFFFFFFFFF in 64 bits; a value that cannot be represented in that width is marked as not fitting.

Can I convert fractions?

Not yet — this converter works on whole numbers, positive or negative. Digits after a decimal point are rejected instead of being silently rounded.

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