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Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteExcel’s LET function gives names to values or calculations inside a single formula, then uses those names in the final calculation. For example, =LET(x, 5, SUM(x, 1)) returns 6: Excel assigns 5 to x, then adds 1. LET is useful when a formula repeats an expression or when naming its intermediate steps makes it easier to read.
What does Excel’s LET function do?
LET assigns names to calculation results or values within a formula. The names are local to that formula: they do not create workbook-wide names or reusable functions. Microsoft describes LET as a way to make formulas easier to understand and to avoid writing the same expression repeatedly. Microsoft’s LET function reference explains the syntax and examples.
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Instead of embedding a complicated expression several times, you can give it a descriptive name once and refer to that name later in the formula. That makes the formula’s stages more visible and can make later edits less error-prone.
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Understand the syntax
Microsoft gives the syntax as:
=LET(name1, name_value1, calculation_or_name2, [name_value2, calculation_or_name3...])
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Read it as a sequence of name-and-value pairs followed by a final calculation that returns the result. You need at least one pair. LET supports up to 126 name/value pairs.
- Name: a label you will use inside the formula.
- Value: a value, cell reference, range, or calculation assigned to that name.
- Final calculation: the expression that uses the names and returns the formula’s result.
The smallest example is =LET(x, 5, SUM(x, 1)). Excel assigns the value 5 to x, evaluates SUM(x,1), and returns 6.
Choose valid, useful names
Names must follow Excel’s defined-name rules. Microsoft notes that a name must start with a letter and cannot conflict with range syntax; for example, c is invalid because it conflicts with R1C1-style references. In longer formulas, names such as taxRate, filteredRange, or netSales tell readers more than single-letter labels.
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Build a formula in stages
Consider a sales table in A2:D8, with the salesperson’s name in column A. This formula filters the table for “Fred” and displays a dash where the filtered result is blank:
=LET(filterCriteria,"Fred", filteredRange,FILTER(A2:D8,A2:A8=filterCriteria), IF(ISBLANK(filteredRange),"-",filteredRange))
The first pair assigns "Fred" to filterCriteria. The second assigns the matching rows to filteredRange. The final calculation checks that range and substitutes a dash for blank results. Naming the criterion and filtered data makes the formula’s sequence easier to inspect or change.
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Can LET make formulas more efficient?
When a formula repeats the same expression, Excel may calculate that expression more than once. LET lets you assign the expression to a name and reuse the name. Microsoft describes this as calculating the named result once, rather than repeating the same calculation in the formula.
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Microsoft’s 2020 Excel Blog announcement says its LET version of a particular sales-filter example ran “twice as fast” as the original. That result applies to Microsoft’s specific example; it is not a general benchmark or a guarantee that LET will speed up every workbook. The more dependable reason to use LET is often clarity: named intermediate results make a complex formula easier to follow.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Does LET work in Excel for the web?
Microsoft lists LET for Excel for Microsoft 365, Excel 2024, and Excel 2021, including the Mac editions covered by its LET reference. However, Microsoft’s Excel functions by category page says LET is not available in Excel for the web. If you work in a browser, check Microsoft’s current function listing for the latest availability information.
When should you use LET instead of LAMBDA?
Use LET to name intermediate values within one formula. If you want to create a custom function that can be reused by name elsewhere, use LAMBDA. Microsoft’s LAMBDA function reference describes creating reusable custom functions and placing a tested LAMBDA in Name Manager. LET does not require that setup; its names exist only inside the formula where you define them.
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