Excel Intermediate Lesson 8: LET for Readable, Faster Formulas

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📘 Excel Intermediate Course · Lesson 8 of 12

LET gives names to pieces of a formula, inside the formula. The result is shorter, easier to check, and faster, because each piece is calculated once.

Before and after

Before: =SUMIFS(K:K,D:D,"North")/SUM(K:K)*100 - IF(SUMIFS(K:K,D:D,"North")/SUM(K:K)>0.3, 5, 0)
After:  =LET(north, SUMIFS(K:K,D:D,"North"),
             total, SUM(K:K),
             share, north/total,
             share*100 - IF(share>0.3, 5, 0))

Pattern: LET(name1, value1, name2, value2, ..., final_calculation). The last argument is always the result.

Real uses

Debugging a LET

Change the last argument to one of the names, e.g. replace the final calculation with s, to see that intermediate result. Then put the calculation back.

Common mistakes

• Names that look like cells (tax1, gst18) give #NAME?. Use tax_amt.
• Forgetting the final calculation: an even number of arguments means the result is missing.

Practice

Download this lesson’s workbook below. Write each one without LET first, then rewrite it. Type your formula in the yellow column; the Check column turns green when the result matches, and the Answers sheet has a working formula for every task.