Trimmed Mean Calculator
Drop the extremes and average what's left.
Enter your values
Enter the data values you are working with.
Enter the trim from each end in %.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Trimmed mean
- 9.5
- Plain mean
- 13.375
- Median
- 9.5
- Values removed from each end
- 1
- Values kept
- 7, 8, 9, 10, 11, 12
- Difference from the plain mean
- -3.875
Quick answer
A trimmed mean discards a set percentage of the smallest and largest values before averaging, giving a figure that resists outliers.
trim k% from each tail, then take the mean
At a glance
| What it does | Drop the extremes and average what's left. |
|---|---|
| Category | Statistics |
| Inputs needed | Data values, Trim from each end |
| Main output | Trimmed mean |
| Formula | trim k% from each tail, then take the mean |
| Cost | Free — no sign-up, no download |
How to use the Trimmed Mean Calculator
- 1Paste your data.
- 2Choose how much to trim from each tail — 10% is a common default.
- 3Compare the trimmed mean with the plain mean to see how much the extremes were pulling the average.
Inputs explained
- Data values
- Enter the data values you are working with.
- Trim from each end(%)
- Enter the trim from each end in %.
Worked example
Using the values the calculator loads with:
Inputs
- Data values5, 7, 8, 9, 10, 11, 12, 45
- Trim from each end12.5 %
Results
- Trimmed mean9.5
- Plain mean13.375
- Median9.5
- Values removed from each end1
- Values kept7, 8, 9, 10, 11, 12
- Difference from the plain mean-3.875
Frequently asked questions
Where is this used in real life?
Olympic gymnastics and diving scores, inflation measures such as trimmed-mean CPI, and any benchmark with noisy outliers.
What trim percentage should I pick?
10% to 20% from each end is typical. Trim 50% and you have simply computed the median.
What do I need to enter into the Trimmed Mean Calculator?
Just 2 values: data values, trim from each end. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Trimmed Mean Calculator work out the answer?
A trimmed mean discards a set percentage of the smallest and largest values before averaging, giving a figure that resists outliers. It applies the formula trim k% from each tail, then take the mean and shows the working so you can check each step by hand.
Is the Trimmed Mean Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.