In this comprehensive guide, we will explore the LET function in Excel, which is a powerful formula that allows you to assign names to calculation results and use them in other formulas. This can significantly improve the readability and maintainability of your Excel formulas. We will cover the syntax, examples, tips and tricks, common mistakes, troubleshooting, and related formulae for the LET function.

LET Syntax

The syntax for the LET function in Excel is as follows:

LET(name1, value1, [name2], [value2], …, calculation)


  • name1 is the name you want to assign to the first value or calculation.
  • value1 is the value or calculation you want to assign to the first name.
  • name2 and value2 are optional and can be used to assign additional names and values or calculations.
  • calculation is the final calculation that uses the assigned names.

LET Examples

Here are some examples of how to use the LET function in Excel:

Example 1: Basic usage

Suppose you want to calculate the area of a rectangle with a length of 10 and a width of 5. You can use the LET function to assign names to the length and width, and then use these names in the calculation:

=LET(length, 10, width, 5, length * width)

This formula will return the area of the rectangle, which is 50.

Example 2: Using multiple names

Imagine you want to calculate the total cost of a purchase, including a 10% discount and 5% sales tax. You can use the LET function to assign names to the original price, discount rate, and tax rate, and then use these names in the calculation:

=LET(price, 100, discount, 0.1, tax, 0.05, price * (1 – discount) * (1 + tax))

This formula will return the total cost of the purchase, which is 94.5.

LET Tips & Tricks

Here are some tips and tricks to help you get the most out of the LET function in Excel:

  1. Use descriptive names for your variables to make your formulas more readable and easier to understand.
  2. When using multiple names, make sure to separate each name and value pair with a comma.
  3. Remember that the LET function can be used in combination with other Excel functions to create more complex formulas.
  4. Use the LET function to simplify repetitive calculations by assigning a name to the result and reusing it in the formula.

Common Mistakes When Using LET

Here are some common mistakes to avoid when using the LET function in Excel:

  1. Forgetting to separate name and value pairs with commas.
  2. Using the same name for multiple values or calculations, which can cause unexpected results.
  3. Not using descriptive names for your variables, making your formulas harder to understand and maintain.
  4. Trying to use the LET function in versions of Excel that do not support it (the LET function is only available in Excel for Microsoft 365).

Why Isn’t My LET Function Working?

If your LET function is not working as expected, consider the following troubleshooting steps:

  1. Check your formula for syntax errors, such as missing or extra commas.
  2. Ensure that you are using the correct names for your variables and that they are not being overwritten by other names in the formula.
  3. Verify that your calculations are correct and that you are using the appropriate Excel functions.
  4. Make sure you are using a version of Excel that supports the LET function (Excel for Microsoft 365).

LET: Related Formulae

Here are some related Excel functions that can be used in conjunction with the LET function:

  1. SUM: Adds all the numbers in a range of cells.
  2. AVERAGE: Calculates the average of the numbers in a range of cells.
  3. IF: Returns one value if a condition is true and another value if it’s false.
  4. VLOOKUP: Searches for a value in the first column of a table and returns a value in the same row from a specified column.
  5. INDEX: Returns the value of an element in a table or an array, based on the row and column numbers you specify.

By combining the LET function with these related functions, you can create more advanced and efficient formulas in Excel.


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