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NORM.S.INV Function

Q: What range of values can probability accept?

Probability must be greater than 0 and less than 1. Values ≤0 or ≥1 return #NUM! error.

Q: What's the difference between NORM.S.INV and NORM.INV?

NORM.S.INV uses standard normal (mean=0, std=1). NORM.INV allows custom mean and standard deviation.

Q: Does it calculate one-tailed or two-tailed values?

It calculates the one-tailed inverse. For two-tailed, divide alpha by 2.

Excel 2010+

Summary

The NORM.S.INV function returns the inverse of the standard normal cumulative distribution, finding the z-score that corresponds to a given probability under a normal distribution with mean 0 and standard deviation 1.

Syntax

NORM.S.INV(probability)

Parameters

Parameter	Type	Required	Description
probability	`Number`	Yes	Probability value (0 < probability < 1) representing cumulative distribution area

Using the NORM.S.INV Function

NORM.S.INV is crucial for determining critical z-values in statistical analysis. Use it to find z-scores for confidence intervals, hypothesis testing p-values, and converting probabilities to standard normal scores.

Common NORM.S.INV Examples

Basic Z-Score Calculation

=NORM.S.INV(0.908789)

Returns approximately 1.3333, the z-score where 90.88% of the distribution lies to the left.

Confidence Interval (95%)

=NORM.S.INV(0.975)

Returns z-score of ~1.96 for 95% confidence interval upper bound.

P-Value to Z-Score

=NORM.S.INV(0.05)

Returns z-score of ~-1.645 for 5% left-tail probability.

Frequently Asked Questions

Probability must be greater than 0 and less than 1. Values ≤0 or ≥1 return #NUM! error.

NORM.S.INV uses standard normal (mean=0, std=1). NORM.INV allows custom mean and standard deviation.

It calculates the one-tailed inverse. For two-tailed, divide alpha by 2.

Common Errors and Solutions

#VALUE!

Cause: Probability argument is non-numeric

Solution: Ensure probability is a valid number

#NUM!

Cause: Probability ≤ 0 or ≥ 1

Solution: Use probability values strictly between 0 and 1

Notes

If probability = 0.5, returns exactly 0 (mean of standard normal)
Uses iterative algorithm matching NORM.S.DIST precision
Available only in Excel 2010 and later versions
Perfect complement to NORM.S.DIST function

Compatibility

Available in: Excel 2010, Excel 2013, Excel 2016, Excel 2019, Excel 2021, Microsoft 365

Not available in: Excel 2007 and earlier

Content last reviewed: December 9, 2025
Update frequency: As needed
Excel versions tested: Excel 2010+