By Carter McBride
Updated March 24, 2022

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A logarithm with a base other than 10 is called a base‑b logarithm. To evaluate logb(x) on a graphing calculator, follow these steps. We’ll label the base as b and the argument as x.

Step 1: Press the LOG button

Most graphing calculators have a dedicated LOG key for natural logarithms. This key is used to initiate the calculation.

Step 2: Enter the argument x

Type the value you wish to log.

Step 3: Close the argument with a right parenthesis

Press the ) key.

Step 4: Divide by the logarithm of the base

Press the division sign ÷.

Step 5: Enter the base b

Type the base value.

Step 6: Close the base expression

Press ) again. The display should now read log(x)/log(b).

Step 7: Execute the calculation

Press = to obtain the result.

By following these steps, you can compute any logarithm with a custom base on a standard graphing calculator.