# Logarithm Calculator

Logarithm calculator online. Calculate logarithm of a number to any base.

## Logarithm calculator

Enter base b and number x and press the = or calculate button:

 log Result:

* Use e for scientific notation. E.g: 5e3, 4e-8, 1.45e12

When:

b y = x

Then the base b logarithm of a number x:

logb x = y

## Anti-logarithm calculator

In order to calculate log-1(y) on the calculator, enter the base b (10 is the default value, enter e for e constant), enter the logarithm value y and press the = or calculate button:

 Result:

When

y = logb x

The anti logarithm (or inverse logarithm) is calculated by raising the base b to the logarithm y:

x = logb-1(y) = b y

### Logarithm rules

#### Logarithm product rule

logb(x × y) = logb(x) + logb(y)

#### Logarithm quotient rule

logb(x / y) = logb(x) - logb(y)

#### Logarithm power rule

logb(x y) = y × logb(x)

#### Logarithm base switch rule

logb(c) = 1 / logc(b)

#### Logarithm base change rule

logb(x) = logc(x) / logc(b)

Logarithm - log(x) ►