Average Calculator
Calculate arithmetic, geometric, harmonic, and weighted averages from any set of numbers.
| # | Value | Dev from Mean | Rank |
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Calculate the arithmetic mean plus geometric mean, harmonic mean, weighted mean, median, and other summary statistics from any list of numbers.
How Average Calculator Works
The arithmetic mean is the sum of all values divided by how many there are. The median is the middle value once the numbers are sorted — or the average of the two middle values when there's an even count.
The geometric mean (the nth root of the product of all values) and harmonic mean (n divided by the sum of each value's reciprocal) are both computed only when every entered number is positive, since taking roots or reciprocals of negative or zero values isn't mathematically valid here. The weighted mean requires a matching list of weights and computes Σ(value × weight) ÷ Σ(weights).
The results table also ranks every entered value from largest (rank 1) to smallest, and shows how far each one deviates from the arithmetic mean — useful for spotting outliers at a glance.
See It In Action
Who Uses Average Calculator and Why
- Comparing arithmetic, geometric, and harmonic means on the same dataset to see which best represents a set of investment returns or rates.
- Computing a weighted average, like a final grade where different assignments count for different percentages.
- Using the median instead of the arithmetic mean when a dataset contains outliers that would otherwise skew a simple average.
- Spotting outliers at a glance using the per-value rank and deviation-from-mean columns in the results table.
Mistakes to Avoid
- Using the arithmetic mean for values that grow multiplicatively over time, like investment returns — the geometric mean correctly accounts for compounding, while the arithmetic mean overstates it.
- Entering negative or zero values and expecting a geometric or harmonic mean — both require every value to be positive, since they involve roots or reciprocals that break down otherwise.
- Supplying a weights list that doesn't match the count of values for a weighted mean, which prevents the Σ(value × weight) ÷ Σ(weights) calculation from lining up correctly.
Tips for Best Results
- Reach for the geometric mean specifically for growth rates or investment returns, where compounding effects matter.
- Check the deviation-from-mean column first when you suspect a single unusual value might be distorting your arithmetic mean.
Fixing Common Problems
Geometric and harmonic mean aren't showing up in my results. — Both require every entered number to be strictly positive — check your list for any zero or negative values, which make those two means mathematically undefined here.
The weighted mean isn't calculating. — Make sure you've entered exactly one weight per value, in the same order as your numbers list.
Terms Explained
Geometric mean: The nth root of the product of all values, best suited to multiplicative data like growth rates.
Weighted mean: An average where each value is scaled by an assigned weight before combining, giving some values more influence than others.