Syntax
LET(name1, value1, [...], calculation)
| Parameter | Description |
|---|---|
| name1 | Parameter of the LET function. |
| value1 | Parameter of the LET function. |
| [...] | (Optional.) Parameter of the LET function. |
| calculation | Parameter of the LET function. |
Examples
Avoid repeated calculations
Formula
=LET(total, SUM(A1:A100), avg, total/COUNTA(A1:A100), IF(avg>50, "Above", "Below"))
'Above' or 'Below'. Calculates total once, uses it to compute average, then evaluates the condition — more efficient than nesting SUM twice.
Named intermediate range
Formula
=LET(data, FILTER(A1:C100, B1:B100>1000), SORT(data, 3, -1))
Filters the data once into a named variable, then sorts it. Without LET, you'd nest SORT(FILTER(...)) which is harder to read and debug.
Tax calculation with named rates
Formula
=LET(price, B2, taxRate, 0.0875, shipping, 5.99, price*(1+taxRate)+shipping)
Calculates total cost using named values for clarity. Each variable name documents what the number represents.
Common Errors
#VALUE!
Odd number of arguments (each name needs a value), or a name is not a valid identifier.
#CALC!
One of the named calculations produces an error that propagates to the final result.
Tips
Performance benefit
If you use SUM(A:A) three times in a formula, it's calculated three times. With LET(s, SUM(A:A), ...), it's calculated once. This matters with large datasets.
Names must be valid identifiers
Variable names can't contain spaces or start with numbers. Use camelCase like 'totalSales' or underscores like 'total_sales'.
Stack multiple variables
LET(a, 1, b, 2, c, a+b, c*10) — you can define many variables, and later variables can reference earlier ones. The last argument is always the return value.
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