Average Calculator

In everyday usage, 'average' typically refers to the arithmetic mean: the sum of all values divided by the count. The term 'mean' can also refer to other averages (geometric, harmonic), but 'average' almost always means the arithmetic mean.

A weighted average accounts for the relative importance (weight) of each value. Instead of dividing by count, you multiply each value by its weight, sum the results, then divide by the total weight. GPA is a common example — grade points are weighted by credit hours.

Use weighted average when some values are more important than others. Examples include: GPA (credits as weights), investment portfolio returns (dollar amounts as weights), survey results (sample sizes as weights).

Adding a value above the current average increases the average; adding one below decreases it. The new average = (old average × old count + new value) / (old count + 1).

You can use percentages as weights directly — the formula normalizes by the total weight. For example, weights of 30%, 50%, 20% work the same as weights of 3, 5, 2. The weighted average will be identical either way.