The base of logarithms can be changed from one that is not 10 or e to an equivalent logarithm with base 10 or e. The following gives the formula for such a transition, in which a, b, and x are real positive numbers (but neither a nor b are equal to 1, and x is greater than 0):

Convert log_a x to the base b by using the formula (log_bx)/(log_ba).