Z-Scores in Excel

Excel computes everything the z table does — here’s the complete formula set, assuming your data lives in A2:A100.

Step 1 — mean and standard deviation

=AVERAGE(A2:A100) → mean (put in E1)
=STDEV.P(A2:A100) → population σ, or
=STDEV.S(A2:A100) → sample s (the n−1 version — which one?)

Step 2 — the z-score

=(A2 - $E$1) / $E$2 — manual version, or the built-in:
=STANDARDIZE(A2, $E$1, $E$2)

Fill down the column and every value gets its z-score. The dollar signs lock the mean/σ cells so the fill works.

Step 3 — z to probability (the table, as a function)

=NORM.S.DIST(z, TRUE) → P(Z < z), exactly what the z table shows
=1 - NORM.S.DIST(z, TRUE) → right tail
=2*(1-NORM.S.DIST(ABS(z), TRUE)) → two-tailed p-value
=NORM.S.INV(0.95) → reverse lookup: the z for a given probability (returns 1.645)

Sanity checks

NORM.S.DIST(1.96,TRUE) should return 0.9750, and NORM.S.INV(0.975) should return 1.96 — the same values as our table, because it’s the same math. Common errors: mixing STDEV.P with sample logic, forgetting TRUE (FALSE gives the density curve, not the probability), and unanchored references breaking the fill-down.