Excel LET Function

last modified April 4, 2025

The LET function is a powerful Excel feature that allows you to assign names to calculation results. This improves formula readability and performance by avoiding redundant calculations. This tutorial provides a comprehensive guide to using the LET function with detailed examples. You'll learn basic syntax, practical applications, and advanced techniques.

LET Function Basics

The LET function assigns names to intermediate calculations or values within a formula. These names can then be referenced multiple times in the formula. The syntax is structured and logical.

Component	Description
Function Name	LET
Syntax	=LET(name1, value1, [name2, value2], ..., calculation)
Arguments	Pairs of names/values followed by calculation
Return Value	Result of final calculation expression

This table breaks down the essential components of the LET function. It shows the function name, basic syntax format, argument structure, and return value characteristics.

Basic LET Example

This example demonstrates the simplest use of the LET function to assign a value to a name and use it in a calculation.

Basic LET formula

=LET(x, 10, x * 2)

This formula assigns the value 10 to the name 'x', then calculates x * 2. The result will be 20. This shows how LET can store intermediate values for reuse.

LET with Multiple Variables

LET can define multiple variables in a single formula. This example shows how to use several named values in a calculation.

A	B
5
10
	=LET(a, A1, b, A2, a + b)

The table shows a simple spreadsheet with values in column A and a LET formula in cell B3 that assigns names to cell values and performs a calculation.

LET with multiple variables

=LET(a, A1, b, A2, a + b)

This formula assigns A1 to 'a' (5), A2 to 'b' (10), then calculates a + b. The result will be 15. Multiple variables make complex formulas more manageable.

LET with Complex Calculations

LET shines when used with complex calculations that would otherwise require duplicate expressions. This example calculates a weighted average.

A	B	C
80	0.3
90	0.5
70	0.2
		=LET(scores, A1:A3, weights, B1:B3, SUM(scores*weights))

This table demonstrates using LET to name ranges and avoid repeating them in the calculation. The formula computes a weighted average of scores.

LET with weighted average

=LET(scores, A1:A3, weights, B1:B3, SUM(scores*weights))

This formula assigns ranges to names 'scores' and 'weights', then calculates the weighted sum. The result is (80*0.3 + 90*0.5 + 70*0.2) = 83. LET makes such formulas more readable.

LET with Conditional Logic

LET can combine with IF to create readable conditional formulas. This example determines a discount based on purchase amount.

LET with IF condition

=LET(total, A1,
     discount, IF(total>100, 0.2, IF(total>50, 0.1, 0)),
     total * (1 - discount))

This formula assigns the purchase amount to 'total', calculates the appropriate discount, then applies it. For A1=120, the result is 96 (20% discount). LET makes the logic clear by separating steps.

LET for Performance Optimization

LET improves performance by calculating values once and reusing them. This example shows how it avoids redundant calculations.

A	B
100
200
	=LET(avg, AVERAGE(A1:A2), COUNTIF(A1:A2, ">"&avg) + COUNTIF(A1:A2, "<"&avg))

The table shows how LET calculates the average once and reuses it, rather than computing it twice in COUNTIF functions. This optimization becomes more valuable with complex calculations.

LET for performance

=LET(avg, AVERAGE(A1:A2), 
     COUNTIF(A1:A2, ">"&avg) + COUNTIF(A1:A2, "<"&avg))

This formula calculates the average of A1:A2 (150) once as 'avg', then counts values above and below it. The result is 2 (100<150 and 200>150). Without LET, AVERAGE would be calculated twice.

LET with Dynamic Arrays

LET works well with dynamic array functions in modern Excel. This example filters and processes data efficiently.

LET with FILTER

=LET(data, FILTER(A1:A10, B1:B10="Yes"),
     avg, AVERAGE(data),
     STDEV.P(data)/avg)

This formula filters values where B1:B10="Yes", calculates their average, then computes the coefficient of variation. LET makes each step clear and avoids repeating the FILTER operation.

The LET function is a powerful tool for creating readable, efficient Excel formulas. By naming intermediate calculations, you can build complex logic while maintaining clarity. LET improves both performance and maintainability, especially in large workbooks. Mastering LET will significantly enhance your Excel formula skills.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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