The Logarithm is the inverse operation to exponentiation. Suppose we have the exponentiation N=x^a, then the logarithm of N with base a equals to x, or x=log_{a}{N}
To compute the logarithm with an arbitrary base just enter your number and base in the corresponding calculator fields:

LogarithmCreative Commons Attribution/Share-Alike License 3.0 (Unported)

The calculator uses the following formula to get the algorithm with arbitrary base:
log_a b =\frac{log_c b}{log_c a}

In addition the calculator gives a base-10 logarithm (common logarithm) and natural logarithm of the given number.