Array Formulasintermediate
Calculate a weighted average with SUMPRODUCT
=SUMPRODUCT(B2:B10,C2:C10)/SUM(C2:C10)
Excel how-to guide
How to let reuse calculation in Excel
Simplify a long nested formula by naming repeated sub-expressions, or avoid calculating the same range lookup multiple times in a single formula.
Step-by-step instructions
How to let reuse calculation — 3 steps
1
List name-value pairs first — each name followed by its expression.
2
After all name-value pairs, enter the final calculation that uses those names.
3
LET calculates each name once and reuses the result wherever that name appears.
Example data
Worked example
| Parameter | Value |
|---|---|
| Annual Rate | 6% |
| Term (years) | 30 |
| Loan Amount | 300000 |
| Monthly Payment | =LET(r,6%/12,n,30*12,PMT(r,n,-300000)) |
Common mistakes
Errors to watch out for
LET is not available
LET requires Excel 365 or Excel 2021. It is not available in Excel 2019 or earlier.
Circular name reference
A name cannot reference itself or a name defined later in the same LET. Define names in the order they are needed.
FAQ
Frequently asked questions
How many names can LET hold?
LET supports up to 126 name-value pairs in a single formula, which is far more than any practical use case requires.
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Array Formulasintermediate
Filter rows by a condition with FILTER
=FILTER(A2:C100,B2:B100="East","No results")