Average Calculator
This average calculator adds a list of numbers and divides by the count to find the arithmetic mean. Switch to weighted average when observations contribute in different proportions.
Enter values separated by commas, spaces, or semicolons. The result includes the sum, count, median, minimum, maximum, and the formula with the current values substituted.
Average
22.5
Formula and substitution: Σx ÷ n = 90 ÷ 4 = 22.5
Sum: 90
Count: 4
Median: 21.5
Minimum and maximum: 12 — 35
How to calculate the arithmetic mean
Add every value and divide the total by the number of values: x̄ = Σx ÷ n. For 12, 18, 25, and 35, the sum is 90 and the count is 4, so the mean is 90 ÷ 4 = 22.5.
Zeros and negative numbers count like any other observation. The average of −5, 0, and 8 is 1 because (−5 + 0 + 8) ÷ 3 = 1.
Weighted average calculator
A weighted mean gives each value its own influence. Multiply each value by its weight, add the products, and divide by the total weight: x̄ = Σ(x × w) ÷ Σw.
For grades 70, 80, and 95 with weights 1, 2, and 3, the result is (70 × 1 + 80 × 2 + 95 × 3) ÷ 6 = 515 ÷ 6 ≈ 85.833. A zero weight excludes a value; negative weights are rejected.
Average calculation examples
| Values | Sum | Average |
|---|---|---|
| 5, 10, 15 | 30 | 10 |
| 12, 18, 25, 35 | 90 | 22.5 |
| −5, 0, 8 | 3 | 1 |
| 60, 75, 90, 100 | 325 | 81.25 |
| 1.5, 2.5, 4 | 8 | 2.666667 |
Mean versus median
The median is the middle of a sorted list. For 2, 3, 4, 5, and 100, the mean is 22.8 while the median is 4. The large outlier pulls the mean upward but does not move the central observation very far.
For a roughly symmetric distribution without extreme values, mean and median may be close. For income, wait times, and other skewed data, showing both gives a more useful summary.
Grade averages and percentages
- Use an arithmetic mean when every assignment has equal weight.
- Use weighted average for exams, projects, or credits with different contributions.
- Percentages can be averaged directly only when their denominators or bases are equivalent; otherwise use those bases as weights.
- The calculator returns the numerical grade average but does not assume a school-specific letter-grade scale.
Frequently asked questions
How do I calculate an average?
Add all values and divide by how many values there are. The average of 10, 20, and 30 is 60 ÷ 3 = 20.
How do I calculate a weighted average?
Multiply each value by its weight, add those products, and divide by the sum of the weights.
Does zero count in an average?
Yes. Zero is a value and is included in the count, so the average of 0 and 10 is 5.
Can an average be negative?
Yes. Signed values are added normally. The average of −10 and 4 is −3.
What is the difference between mean and median?
The mean uses the sum of every value; the median is the middle of the sorted list. Extreme values therefore affect the mean more strongly.
Updated: 2026-08-28