Mean Calculator
Add a list of numbers and see the mean with the sum, the count and every substitution in Σx / n. The dataset stays in your browser and carries over to the median, SD, IQR and z-score pages.
- No upload
- Worked steps
- Free, no sign-up
100% Local in Browser — Your Data Never Leaves This Tab
Comma, space, tab or newline separated. Paste an Excel column directly; blank lines and labels are ignored.
Try a sample
Paste a dataset to begin
The worked steps, table, box plot and summary update as you type. Nothing is sent anywhere.
How it works
- 1
Paste once
Commas, spaces, tabs and Excel columns are all accepted. The shared dataset is kept in sessionStorage, so moving from this page to standard deviation does not mean pasting the same homework list again.
- 2
Add and divide
The page prints Σx, n and the full substitution (12 + 15 + … ) / 9. The arithmetic is done on your actual values, not on a canned example.
- 3
Compare with the median
The Quick Summary card puts the mean beside the median, sample SD, IQR and range. If the mean is much larger than the median, an outlier or a skewed tail is usually the reason.
More tools
- Median CalculatorPaste a dataset and get the median with the sorted list, the exact middle position or pair, and a box plot. Odd and even counts are handled separately, and the numbers never leave your browser.
- Standard Deviation CalculatorGet sample or population SD with a row-by-row deviation table, the definition formula and the computational Σx² − n·x̄² formula. Copy the APA result or switch to population variance without re-pasting the data.
- Average CalculatorFind the average of any list with the sum, count and substitution shown line by line. Also called an average finder; the page reports the arithmetic mean and compares it with the median so a skew does not fool you.
- Interquartile Range (IQR) CalculatorCompare Q1, Q2, Q3 and IQR under the TI-83/84/AP exclusive rule, Tukey’s inclusive hinges and Excel QUARTILE.INC interpolation. See the 1.5 × IQR fences, potential outliers and a live box plot.
- Z-Score CalculatorTurn x, μ and σ into a z-score and a left-tail, right-tail or two-tailed probability, or standardize every value in your dataset at once. The standard normal curve fills the same area the table reports.
What it won't do
- The arithmetic mean is sensitive to every value: one extra-large observation moves it. That is a feature for some questions and a trap for others; compare it with the median before deciding.
- Only numeric tokens are read. A blank cell is not treated as zero, because inventing a value would change the denominator without telling you.
- The page reports the mean of the data you pasted. It does not infer a population, a weighted mean, or a frequency table unless you expand the frequencies into repeated values first.
- No account, upload or API call is involved; the browser is the entire runtime.
Questions
What is the formula for the mean?
Add all values to get Σx, then divide by the number of values n: x̄ = Σx / n. The worked steps show both the sum and the division, which is the part most online calculators skip.
What is the difference between mean and average?
In everyday statistics they are the same arithmetic mean. “Average” can also mean median or mode in a casual question, so this page reports the arithmetic mean and the Quick Summary shows the median too.
How does an outlier affect the mean?
It pulls the mean toward itself by its full distance divided by n. The median usually stays put. Load the With Outlier preset and compare the two numbers: the 98 raises the mean but leaves the middle value alone.
Can I paste an Excel column?
Yes. Copy the column and paste it into the box; newlines, commas and tabs are all separators. Labels are ignored, but check the parsed count before trusting the result.
Is the mean the same as the expected value?
For a finite list, the arithmetic mean is the empirical average. An expected value is the probability-weighted long-run mean of a random variable. They use similar notation but answer different questions.
Where did my data go when I changed pages?
It stayed in this browser tab’s sessionStorage. All six WorkedStats calculators read the same key, so the next page opens with the same dataset. Closing the tab clears it.