Trimmed Mean Calculator
Calculate a trimmed mean that discards extreme values before averaging.
About Trimmed Mean Calculator
Trimming a fixed percentage from each tail makes the mean resistant to outliers while retaining more information than the median. A 10 per cent trim tolerates up to 10 per cent contaminated data. Trimmed means are standard in competition scoring and price indices precisely because they resist both accidental and deliberate extreme values.
Formula
Trimmed Mean
Trimmed mean = mean of the values remaining after discarding the top and bottom p%
- breakdown point
- Proportion of contamination the estimator can tolerate
Worked example
With the default values below, Trimmed Mean Calculator returns Trimmed Mean of 50.62500. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Sample sizeminimum 3
- 100
- Percentage trimmed from each tailaccepts 0–100 %
- 10 %
- Mean of the full sample
- 52.4
- Sum of the retained values
- 4,050
Results
- Trimmed Mean
- 50.62500
- Values Retained
- 80
- Values Discarded
- 20
- Difference From the Untrimmed Mean
- -1.77500
- Breakdown Point
- 10.00%
Step by step
- 1Values used
- 2Trimmed Mean
- 3Trimmed Mean= 50.62500
- 4Values Retained= 80
- 5Values Discarded= 20
- 6Difference From the Untrimmed Mean= -1.77500
- 7Breakdown Point= 10.00
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 5 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Trimmed Mean calculated?
Trimmed mean = mean of the values remaining after discarding the top and bottom p% Trimming a fixed percentage from each tail makes the mean resistant to outliers while retaining more information than the median. A 10 per cent trim tolerates up to 10 per cent contaminated data.
Why does Trimmed Mean matter?
Trimmed means are standard in competition scoring and price indices precisely because they resist both accidental and deliberate extreme values.
What values do I need to enter?
This calculator takes 4 inputs: Sample size, Percentage trimmed from each tail, Mean of the full sample, Sum of the retained values. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.