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TRIMMEAN Function

Excel 2007+

Summary

The Excel TRIMMEAN function calculates the mean of a dataset by excluding a specified percentage of the highest and lowest values. This trimmed mean provides a more robust average that minimizes the impact of outliers and extreme values in statistical analysis.

Syntax

TRIMMEAN(array, percent)

Parameters

Parameter	Type	Required	Description
array	`Range/Array`	Yes	The range or array containing the numeric data to trim and average
percent	`Number`	Yes	The proportion of data points to exclude from top and bottom tails

Using the TRIMMEAN Function

TRIMMEAN is particularly valuable in statistical analysis where outliers can significantly distort the mean. By trimming extreme values from both ends of the dataset, it provides a more representative central tendency that better reflects the typical values in your data.

Common TRIMMEAN Examples

Basic Outlier Removal

=TRIMMEAN(A2:A12,0.2)

Calculates mean of data in A2:A12 excluding 20% of highest and lowest values (2 points from each end). Result: 3.778

10% Trim for Small Dataset

=TRIMMEAN(B1:B10,0.1)

Trims 10% from both ends of 10 values, excluding 1 highest and 1 lowest value for symmetric analysis

Survey Data Cleaning

=TRIMMEAN(C2:C51,0.15)

Analyzes 50 survey responses, excluding 15% extremes (top/bottom 7-8 values) for representative average

Frequently Asked Questions

TRIMMEAN(array,0) returns the regular AVERAGE of the dataset with no trimming.

No, values outside 0-1 range return #NUM! error.

Exclusions are rounded down to nearest even number and split symmetrically.

Common Errors and Solutions

#NUM!

Cause: Percent < 0 or percent > 1

Solution: Use value between 0 and 1 inclusive

#VALUE!

Cause: Array contains non-numeric values

Solution: Ensure array contains only numbers

#DIV/0!

Cause: Percent excludes all data points

Solution: Use smaller percent value

Notes

Always sorts data internally before trimming
Exclusions rounded down to nearest even number for symmetry
Works with single column ranges or array constants
Ignores text and logical values in array
Empty cells treated as zero

Compatibility

Available in: Excel 2007, Excel 2010, Excel 2013, Excel 2016, Excel 2019, Excel 2021, Microsoft 365

Not available in: Excel 2003 and earlier

Content last reviewed: December 9, 2025
Update frequency: As needed
Excel versions tested: Excel 2007+