What is a Average Calculator?
The average calculator computes the arithmetic mean, weighted average, and median of a set of numbers โ used for grades, scores, and other measurements.
How it's calculated
Arithmetic mean = sum of values รท count
Weighted average = ฮฃ(value ร weight) รท ฮฃ(weight)
When averages lie
Averages are convenient but can distort reality in skewed data. If nine people earn $30,000 and one earns $3 million, the average exceeds $300,000 โ but the median of $30,000 reflects the group's reality far better. That is why income and housing price statistics should always be read alongside the median.
Good to know
- Averaging percentages arithmetically can be wrong. If returns were +50% and โ50%, the average is not 0% but actually about โ13.4% (geometric mean) โ because $100 became $150 then $75.
- Speed averages require the harmonic mean. Driving 60 km/h one way and 30 km/h back over the same distance averages to 40 km/h, not 45.
- This is also why a simple average is wrong for GPA when courses carry different credit weights โ a weighted average is required.
- A classic statistics joke: 'With one foot in ice water and one in boiling water, you're comfortable on average.' A reminder that averages alone can be misleading.
- The English word 'average' is thought to derive from the Arabic awariya (damaged goods), from the old maritime practice of spreading shipping losses evenly among cargo owners.
Frequently asked questions
Q. Should I look at the average or the median?
For skewed data like income or housing prices, the median better reflects reality. For evenly distributed data, the average works fine.
Q. When should I use a weighted average?
When items carry different importance โ GPA (credit weights), grade weighting, or portfolio returns are common examples.
Q. How do you average investment returns?
Use the geometric mean โ multiply the returns together and take the root โ to correctly reflect compounding.