PERCENTILE.INC in Excel: Inclusive Percentiles and Interpolated Cutoffs

• Introduced: the Microsoft function catalogue marks PERCENTILE.INC as an Excel 2010 addition; an exact first build or preview date is not established here.
• Availability: official help lists Excel for Microsoft 365, Excel for Microsoft 365 for Mac, Excel 2024, Excel 2024 for Mac, Excel 2021, Excel 2021 for Mac, Excel 2019, Excel 2016.
• Checked: October 14, 2026; official PERCENTILE.INC reference. Documentation and independently modeled examples; no native Excel execution or broader platform certification.

=PERCENTILE.INC(array, k)

Both arguments are required. array supplies the numeric observations and k identifies a position from 0 through 1. The endpoints include the minimum and maximum. Microsoft documents interpolation between adjacent sorted observations when the requested position does not land on an observation.

For the all-numeric examples here, sort a conceptual copy and use the one-based position 1+(n-1)*k. At an integer position, take that observation. Otherwise move the fractional part of the distance toward the next observation. This is an audit calculation; the worksheet range itself need not be manually sorted.

Enter 0, 10, 30, 60 and 100 in A2:A6. Treat these as fictional elapsed minutes, including a genuine zero-minute record.

The median, 30, is an observed value in this odd-sized dataset. The other percentiles are not promises that exactly the named percentage of records will lie strictly below the returned value.

=PERCENTILE.INC(A2:A6,90%)

Expected result: 84 minutes. The position is 1+4*0.9=4.6, so interpolate between the fourth value, 60, and the fifth, 100: 60+0.6*(100-60)=84.

There is no 84-minute record. A percentile can be a useful reporting threshold without being a value that appears in the data. Formatting 84 as a percentage would misrepresent its meaning.

Place =PERCENTILE.INC(A2:A6,0.75) in D2. Then compare:

=COUNTIF(A2:A6,">"&D2)
=COUNTIF(A2:A6,">="&D2)

The counts are 1 and 2. Strictly above 60 includes only 100; at or above 60 includes both 60 and 100. The rule matters even without tied inputs.

In a separate B2:B7 range enter 0, 10, 30, 60, 60 and 100. The 75th percentile is still 60, but an inclusive cutoff now selects three of six records. A fixed row quota needs a separate tie-break policy; changing the percentile convention does not by itself choose among identical measurements.

For the original five values, create C2 with =A2*2+5 and fill through C6. The transformed values are 5, 25, 65, 125 and 205.

=PERCENTILE.INC(C2:C6,0.9)

Expected result: 173, matching 2*84+5. This positive linear transformation is a useful independent consistency check. It does not justify reversing the comparison direction when a transformation reverses the ordering.

Microsoft documents #NUM! for an empty array or k outside 0–1, and #VALUE! for a nonnumeric k. Entering 90 instead of 90% is outside the permitted interval.

The dedicated page does not fully specify all mixed-type, error-valued or one-observation combinations. Those boundaries are not certified by these all-numeric multi-observation examples.

PERCENTILE.EXC uses a different plotting-position convention. QUARTILE.INC requests quarter points of the inclusive convention. Record the chosen function, comparison operator and sample definition alongside a published cutoff.

• Microsoft PERCENTILE.INC reference.
• Editorial testing standards.

Expected results are independent statistical/arithmetic models or explicitly documented rules, not captured native output. Examples use English function names and comma separators. Datasets and reporting policies are fictional.