ToolnozaUnderstand the method
An arithmetic mean gives every observation equal influence. Add the values and divide by their count. For 2, 4 and 6, the sum is 12 and the count is 3, so the mean is 4. Zero is an observation; an empty cell is not automatically a zero. Decide how to handle missing values before calculating.
Worked calculation
A weighted mean gives different influence to each observation. With values 2, 4, 6 and weights 1, 1, 2, calculate (2 × 1 + 4 × 1 + 6 × 2) ÷ (1 + 1 + 2) = 18 ÷ 4 = 4.5. The weights need not sum to 100, but they must be nonnegative and have a positive total.
Practical checks
Sort values to find the median. For 2, 4, 6, 100, the median is (4 + 6) ÷ 2 = 5 while the mean is 28. A large observation affects the mean more strongly. If a group of 10 averages 80 and a group of 30 averages 60, the combined mean is 65, not 70: use group sizes as weights.
Use the free tool
Enter numbers separated by spaces, semicolons or new lines. Use decimal points. Add one weight per number for a weighted mean.
Formula reference
Mean = sum / count. Weighted mean = Σ(value × weight) / Σweights. Median is the middle sorted value, or the mean of the two middle values.
Limits
Weights must be nonnegative with a positive total. Median is unweighted. This is not a geometric mean or compound return calculator.