STDEV.P Function in Excel

Excel’s STDEV.P function returns the standard deviation for an entire population.

It measures how widely values spread around their mean in the original units.

A lower standard deviation means the population values sit closer together.

In this article, I’ll show you how to measure population variation, compare STDEV.P with STDEV.S, and calculate standard deviation for a selected group.

STDEV.P Function Syntax in Excel

STDEV.P requires one numeric argument and accepts up to 253 more.

=STDEV.P(number1, [number2], ...)
  • number1 is the first number, range, array, or reference for the population.
  • number2, through argument 254, are optional additional numbers, ranges, arrays, or references from the same population.

When to Use STDEV.P Function

  • Measure variation when the listed values are the complete population of interest.
  • Compare consistency across complete groups or processes.
  • Calculate population spread for one filtered segment.
  • Combine several complete ranges into one population calculation.
  • Report variation in the same units as the source data.

Example 1: Calculate Population Standard Deviation

This example measures output variation across every packing station in one full shift.

Below is the dataset with all eight station totals and an empty population-standard-deviation result cell.

STDEV.P Example 1 dataset

We want to measure the spread across this complete set of station totals.

Here is the formula:

=STDEV.P(B2:B9)
=STDEV.P(B2:B9) in B11

The population standard deviation is 2.29 units. That describes the variation across all eight stations included in the shift report.

Pro Tip: Define the population before choosing the function. A complete shift can be a population even when it represents only one day.

Example 2: Compare STDEV.P and STDEV.S

The right function depends on whether the values are a population or a sample.

Below is the dataset with on-time deliveries for every hub in the reporting group and two empty result cells.

STDEV.P Example 2 dataset

We first want the standard deviation for the complete six-hub population.

Here is the STDEV.P formula:

=STDEV.P(B2:B7)
=STDEV.P(B2:B7) in B9

STDEV.P returns 7.56 because the six values are the entire group being described.

For comparison, suppose those hubs were only a sample selected from a larger network.

Here is the STDEV.S formula:

=STDEV.S(B2:B7)
=STDEV.S(B2:B7) in B10

STDEV.S returns 8.29. It divides by n-1 to estimate variation in a larger population, while STDEV.P divides by n.

Pro Tip: Do not choose STDEV.P because its result is smaller. Choose it only when the data covers the complete population you want to describe.

Example 3: Compare Process Consistency

Population standard deviations make complete groups easier to compare.

Below is the dataset with every daily cycle-time record for two production lines and two empty result cells.

STDEV.P Example 3 dataset

We want to measure Line Alpha’s variation across the full week.

Here is the formula:

=STDEV.P(B2:B8)
=STDEV.P(B2:B8) in B10

Line Alpha has a population standard deviation of 0.16 minutes.

We also want the same measure for Line Beta.

Here is the second formula:

=STDEV.P(C2:C8)
=STDEV.P(C2:C8) in B11

Line Beta’s population standard deviation is 2.17 minutes. Alpha is more consistent because its cycle times have much less spread.

Pro Tip: Compare standard deviations only when the measurements use the same units and represent populations defined in a comparable way.

Example 4: Calculate Standard Deviation by Group

STDEV.P can reduce a filtered array to one population statistic.

Below is the dataset with response times by region, an East criterion in E2, and an empty result cell in E3.

STDEV.P Example 4 dataset

We want the population standard deviation for all six East-region response times.

Here is the formula:

=STDEV.P(FILTER(B2:B13,A2:A13=E2))
=STDEV.P(FILTER(B2:B13,A2:A13=E2)) in E3

FILTER returns 24, 27, 22, 29, 25, and 30. STDEV.P reduces that array to one result: 2.79 minutes.

FILTER is available in Excel 2021, Excel 2024, Microsoft 365, and Excel for the web. Older versions need a helper range for the selected group.

Example 5: Combine Multiple Population Ranges

STDEV.P can accept several ranges without stacking them into a helper column.

Below is the dataset with every morning and evening shift check from Monday through Saturday and an empty combined result cell.

STDEV.P Example 5 dataset

We want one population standard deviation across all 12 shift checks.

Here is the formula:

=STDEV.P(B2:B7,C2:C7)
=STDEV.P(B2:B7,C2:C7) in B9

The two ranges become one 12-value population. STDEV.P returns a combined standard deviation of 2.39 checks.

Pro Tip: Separate ranges are fine when they belong to one population. Do not combine unrelated groups merely to avoid writing two formulas.

Tips & Common Mistakes

  • Use STDEV.P for a complete population. Use STDEV.S when a sample is meant to estimate a larger population.
  • Avoid the older STDEVP name in new work. STDEV.P is its current replacement.
  • Remember that STDEV.P is a reducer. It accepts arrays but returns one number rather than a spilled list.
  • Referenced empty cells, text, and logical values are ignored. Use STDEVPA when referenced text and logical values must count.
  • Use SQRT(VAR.P(range)) as an audit relationship when working with population variance, not as a longer replacement for STDEV.P.
  • Check that every compared dataset uses the same measurement unit and population definition.

I covered complete-population spread, sample comparison, process consistency, filtered groups, and multiple-range calculations.

I hope you found this article helpful.

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