Logarithm calculator

Solve log_b(x) = y for the missing value — base, argument, or result.

log_b(x) = y

Solves log_b(x) = y for the missing value: x = b^y, b = x^(1/y), y = log(x)/log(b). Change-of-base values are shown for cross-checking. Leave the field you want to solve empty.

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How to use

  1. Fill any two of base b, argument x, and result y.
  2. Leave the field you want to solve empty.
  3. Read the solved value plus ln/log₁₀/log₂ cross-checks.

What it supports

x = b^y, b = x^(1/y), y = log(x)/log(b). The base must be positive and not 1, the argument positive. Quick presets set b to e, 10, or 2. Very large magnitudes may hit floating-point limits.

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