Average Calculator
The average, or arithmetic mean, adds a list of values and divides by how many there are. Some situations call for a weighted average, where certain values count more (like exam scores worth different percentages), or a geometric or harmonic mean (for growth rates and speeds). Enter your numbers, and optionally weights, and this calculator handles all four.
How to use the average calculator
- Type your numbers separated by commas or spaces.
- Optionally type one weight for each number to get a weighted average.
- Read the mean first. The geometric and harmonic means appear when every number is positive.
Formula
- Mean = sum ÷ count
- Weighted average = Σ(value × weight) ÷ Σ(weight)
- Geometric mean = (product of values)1/n
- Harmonic mean = n ÷ Σ(1/value)
Worked examples
Simple mean
Test scores 85, 90 and 78 give (85 + 90 + 78) ÷ 3 = 84.33.
Weighted average
Scores of 90, 80 and 70 with weights 50, 30 and 20 give (4500 + 2400 + 1400) ÷ 100 = 83.
Geometric mean
For growth factors 2 and 8 the geometric mean is √16 = 4, which is the constant factor with the same total growth.
Choosing the right kind of average
| Average | Use it for | Example |
|---|---|---|
| Arithmetic mean | Typical value of similar quantities | Average test score |
| Weighted average | Values that matter unequally | Course grade with different weights |
| Geometric mean | Growth rates and ratios | Average annual return |
| Harmonic mean | Rates over equal distances | Average speed of a round trip |
A worked weighted average
Homework is worth 20%, quizzes 30% and the exam 50%. Scores of 95, 80 and 70 give (95 × 20 + 80 × 30 + 70 × 50) ÷ 100 = 78.
Average speed for a round trip
Driving 60 km/h out and 40 km/h back over the same distance is not an average of 50 km/h. The harmonic mean gives 2 ÷ (1/60 + 1/40) = 48 km/h, which matches total distance divided by total time.
Averages can mislead
A few extreme values can drag the mean far from what is typical. Check the median too, using the statistics calculator, and remember that an average hides how spread out the data is.
Practice problems
Try these yourself first, then check your answer. The answers come from the calculator above.
- Find the mean of 72, 88, 91, 65 and 84.
Show answer
Mean (average): 80
- Scores 95, 80 and 70 have weights 20, 30 and 50. Find the weighted average.
Show answer
Mean (average): 81.66666667 · Weighted average: 78
Common mistakes to avoid
- Averaging percentages without weighting when the groups have different sizes.
- Using the arithmetic mean for growth rates, where the geometric mean is correct.
- Using the arithmetic mean of speeds over equal distances. The harmonic mean is right for that.
Frequently asked questions
How do I calculate an average?
Add all the numbers and divide by how many there are.
What is a weighted average?
An average where some values count more than others, such as a course grade where the final is worth 40%.
When is the geometric mean used?
For growth rates and ratios, like average annual investment return.
What about median and mode?
Use the statistics calculator for median, mode and standard deviation.
Reviewed September 26, 2026 by the SolveCalcPro editorial team. Found a mistake? Tell us; see our editorial policy.