Log

LOG Function

The LOG function in Excel is used to calculate the logarithm of a number to a specified base. This function is versatile and allows you to calculate logarithms for various bases such as 2, 10, or any other positive number.

Syntax:

LOG(number, [base])

• number: The positive numeric value for which you want to calculate the logarithm.
• base (optional): The base of the logarithm. If omitted, the default base is 10.

Examples:

1. =LOG(1000, 10)
   Returns 3, because 10^3 = 1000.

2. =LOG(8, 2)
   Returns 3, because 2^3 = 8.

3. =LOG(81, 3)
   Returns 4, because 3^4 = 81.

4. =LOG(1, 10)
   Returns 0, because 10^0 = 1.

5. =LOG(32, 2)
   Returns 5, because 2^5 = 32.

6. =LOG(100)
   Returns 2, because the default base is 10, and 10^2 = 100.

Usage Notes:

• The number must be positive; otherwise, the function will return a #NUM! error.
• The base must be a positive number and cannot be 1, as logarithms with those values are undefined.
• If base is omitted, Excel assumes a base of 10 (default logarithm base).
• Use the LOG function in various contexts such as mathematical, financial, or scientific computations whenever non-default bases are needed. For simple base-10 logarithms, you may also use the LOG10 function.