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NORM.INV Function

Excel 2010+

Summary

The NORM.INV function returns the inverse of the normal cumulative distribution, finding the value corresponding to a given probability within a specified normal distribution defined by its mean and standard deviation.

Syntax

NORM.INV(probability, mean, standard_dev)

Parameters

Parameter	Type	Required	Description
probability	`Number`	Yes	A probability value between 0 (exclusive) and 1 (exclusive)
mean	`Number`	Yes	The arithmetic mean of the target distribution
standard_dev	`Number`	Yes	The standard deviation of the target distribution

Using the NORM.INV Function

NORM.INV is crucial for statistical applications where you need to find critical values or percentiles in a normal distribution. Use it to determine thresholds, set confidence intervals, or generate random variates matching specific probabilities.

Common NORM.INV Examples

Basic Percentile Calculation

=NORM.INV(0.908789, 40, 1.5)

Returns approximately 42, the value where 90.88% of the distribution falls below (mean=40, sd=1.5)

95th Percentile

=NORM.INV(0.95, 100, 15)

Finds the value exceeded by only 5% of observations in a distribution with mean 100 and SD 15

Z-Score Conversion (Standard Normal)

=NORM.INV(0.975, 0, 1)

Returns ~1.96, commonly used z-score for 95% confidence intervals

Frequently Asked Questions

Returns #NUM! error if probability ≤ 0 or ≥ 1

Yes, use mean=0, standard_dev=1 to get standard normal inverse (equivalent to NORMSINV)

Precision depends on NORM.DIST accuracy; minor rounding differences are normal

Common Errors and Solutions

#VALUE!

Cause: Any argument is non-numeric

Solution: Ensure all inputs are valid numbers

#NUM! (probability)

Cause: Probability ≤ 0 or ≥ 1

Solution: Use probability strictly between 0 and 1

#NUM! (standard_dev)

Cause: Standard deviation ≤ 0

Solution: Standard deviation must be positive

#NUM! (precision)

Cause: Extreme values causing calculation limits

Solution: Check input ranges and use reasonable distribution parameters

Notes

If mean=0 and standard_dev=1, uses standard normal distribution (see NORMS.INV)
Precision matches NORM.DIST function
Ideal for one-tailed critical values and percentiles
Combines powerfully with NORM.DIST for distribution analysis

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 11, 2025
Update frequency: As needed
Excel versions tested: Excel 2010+