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Binary to Decimal Converter

Type binary or decimal numbers, one per line, and they convert instantly.

Your text and files never leave your browser — nothing is sent to a server.

How to use

  1. Choose a direction and type one number per line. Spaces, underscores and the 0b prefix are ignored.
  2. Fractions work both ways: binary 0.101 is decimal 0.625. Decimal fractions that never end in binary (like 0.1) are cut at “Max fraction bits” and marked with “…”.
  3. Pick an 8, 16, 32 or 64-bit width to read or write negative whole numbers in two’s complement (11111111 → -1 in 8-bit).
  4. Turn on “Group binary in 4s” to make long bit strings easier to read.

FAQ

How do you convert binary to decimal by hand?

Multiply each bit by its power of two and add them up. 1011 = 1×8 + 0×4 + 1×2 + 1×1 = 11. After the point the powers are ½, ¼, ⅛…, so 0.101 = 0.5 + 0.125 = 0.625.

Why does 0.1 never end in binary?

Only fractions whose denominator is a power of two terminate in binary. 0.1 is 1/10, so its binary form repeats forever (0.000110011…). This is also why 0.1 + 0.2 is not exactly 0.3 in floating-point maths.

Does the width apply to fractions?

No. Two’s complement is applied only to whole numbers; fractional values keep a minus sign.

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