When to use this calculator
Average a dataset after trimming equal whole-number counts from both tails. The percentage applies to each tail separately and removed counts are rounded down.
Explore the descriptive statistics calculators for other questions in this topic. For a related calculation, use the Weighted Mean Calculator: Combine three values using non-negative weights.
PUTTING IT INTO PRACTICE
Trimmed Mean: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Data values | 1,2,3,4,100 |
| Percentage removed from each tail | 20 |
| Result | 3 |
- Check the input labels and enter the example values above.
- Apply the relationship: Remove floor(N × tail percent/100) values at each end, then average..
- The result is 3 , rounded for display.
How to interpret your result
The percentage applies to each tail separately and removed counts are rounded down.
The mean, median, range and standard-deviation tools accept variable-length lists with their limits stated. Choose a sample or population denominator appropriately. A summary statistic does not validate the sampling process or explain causation.
Frequently asked questions
Should I use sample or population standard deviation?
Use population deviation for the complete population being described. Use the sample form when estimating variability from a sample under suitable assumptions.
When is the trimmed mean calculator useful?
Average a dataset after trimming equal whole-number counts from both tails. The percentage applies to each tail separately and removed counts are rounded down.
How do I use the trimmed mean calculator?
Enter data values, percentage removed from each tail. The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Remove floor(N × tail percent/100) values at each end, then average..
What should I check before using the result?
The percentage applies to each tail separately and removed counts are rounded down.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
Further reading
For background on this topic, see NIST: exploratory data analysis ↗. This is a topic reference, not an external review or endorsement of this tool.
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