Average Calculator
Average (mean) calculator: enter any list of numbers, press Calculate and get the arithmetic mean plus count, sum, median, mode, geometric mean, RMS, population and sample standard deviation, minimum, maximum and range — with the full calculation steps. A weighted average calculator is built in below. Everything runs locally in your browser.
Average calculator
Weighted average calculator
Enter your numbers
Type the data set into the box separated by spaces, commas, semicolons or newlines — e.g. 1 2 5 2 6 6. Negative numbers (-3.5), decimals and scientific notation (1e2) all work.
Press Calculate
The average (mean) appears in its own field with a Copy button, alongside Count, Sum, Median, Mode, Geometric mean, RMS, Population SD, Sample SD, Min, Max and Range, the step-by-step working, and two charts drawn locally from your numbers.
Need a weighted average?
Use the second form: enter a weight and a number per row (Add row for more), press Calculate, and get the weighted average, the sum of the weights and the full expression — e.g. (2×70+3×80+1×90) / (2+3+1) = 78.33333333.
How the average and the statistics work here
- What is the average (arithmetic mean)?
- The mean is the sum of the n numbers divided by n: Average = Sum / Count. For example the average of 1, 2, 5, 2, 6, 6 is (1+2+5+2+6+6) / 6 = 22 / 6 = 3.6666666666667.
- Which other statistics do I get, and what do they mean?
- Median is the middle value of the sorted list (average of the two middle values for an even count). Mode is the most frequent value — ties are listed in ascending order and sets with no repeats show "none". Geometric mean is the n-th root of the product, RMS is the root mean square √(Σx²/n), Population SD divides the squared deviations by n, Sample SD by n−1, and Range = Max − Min.
- Why do some fields show "undefined"?
- Some statistics do not exist for certain data: Sample SD needs at least two numbers (n−1 would be 0), and the geometric mean is only real-valued when every number is positive. The field then shows "undefined" instead of a misleading number.
- How is the weighted average calculated?
- Weighted average x̄ = Σ(wᵢ×xᵢ) / Σwᵢ: each value is multiplied by its weight, the products are summed, and the result is divided by the sum of the weights. For grades 70 (twice), 80 (three times) and 90 (once): (2×70+3×80+1×90) / (2+3+1) = 470 / 6 = 78.33333333. Weights must be 0 or greater, and their sum must be positive.
- What happens if I enter something that is not a number?
- The calculator names the offending token (e.g. "abc" is not a valid number.) or tells you the input is empty, and clears any previous result so a stale answer can never be mistaken for the result of your latest input. The Calculate button always stays pressable — validation happens in the app, not by the browser.
Privacy: every statistic, step and chart is computed and drawn in your browser tab — no value you type is sent anywhere, and the clipboard is only touched when you press Copy. Results use IEEE-754 double-precision arithmetic displayed with 14 significant digits.