Express how many standard deviations a value sits from the mean.
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=(A2-AVERAGE($A$2:$A$100))/STDEV.S($A$2:$A$100)Subtract the mean from the value and divide by the standard deviation. A z-score of 0 is average, +2 is two deviations above, −1 is one below. Lock the range with absolute references so it stays fixed as you fill down.
=(85-70)/12→1.2585 is 1.25 SD above a mean of 70.
=STANDARDIZE(85, 70, 12)→1.25The built-in function gives the same result as the manual formula.
=(58-70)/12→-1A negative z-score means the value is below the mean.
Yes — STANDARDIZE(x, mean, sd) returns the z-score directly.
A common rule flags values with a z-score above 3 or below -3. Use =ABS(B2)>3 to mark them.
Use STDEV.P when your data is the whole population and STDEV.S when it is a sample. The choice changes the z-score slightly.
Use =NORM.S.DIST(B2, TRUE). A z-score of 1.25 corresponds to about the 89th percentile.
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