Logarithm Calculator

Logarithm calculator

Calculate a logarithm in a custom base and also see log10 and ln.

log_b(x) = ln(x) ÷ ln(b), with x > 0, b > 0 and b ≠ 1.

Value is the logarithm argument; base sets the scale. Extra rows show base 10 and e.

The result is the exponent to which the base must be raised to obtain the value.

Practical examples

• log₂(8) = 3; log₁₀(8) ≈ 0.903 and ln(8) ≈ 2.079.

Limitations and notes

• Real logarithms are not defined for zero or negative values.
• Use valid values and keep all units consistent.

How to use

1. 1Enter value and base.
2. 2Review the custom logarithm.
3. 3Compare log10 and ln.

Frequently asked questions