How to find the average
Mean = Sum of all values ÷ Count of values Example: test scores of 85, 90, 78, 92, 88 Sum = 85 + 90 + 78 + 92 + 88 = 433 Mean = 433 ÷ 5 = 86.6 When people say "average" without qualifying it, they almost always mean this one — add everything up, divide by how many numbers there are.
Mean vs. median — they're not the same "average"
The median is the middle value once everything is sorted — and it can differ substantially from the mean when a data set has extreme outliers.
$40,000, $45,000, $48,000, $50,000, $400,000 Mean = (40,000+45,000+48,000+50,000+400,000) ÷ 5 = $116,600 Median = the middle value once sorted = $48,000 The mean here is pulled far above what four of the five people actually earn, because one large value drags it upward. The median isn't affected by outliers the same way, which is why income, home prices, and similarly skewed data are often reported as medians rather than means — the median better represents a "typical" value when a few extreme numbers would otherwise distort the picture.
Mode and range
Mode is the value that appears most often. A list can have one mode, several tied modes, or no mode at all if every value is unique. Range is simply the largest value minus the smallest — a quick measure of how spread out the data is.
Weighted average
A plain average treats every number equally. A weighted average doesn't — some values count more than others, like a final exam worth more of a grade than a single homework assignment.
Weighted Average = Σ(value × weight) ÷ Σ(weight) Example: exam 90 (worth 30%), homework 85 (worth 20%), final 95 (worth 50%) = (90×30 + 85×20 + 95×50) ÷ (30+20+50) = (2,700 + 1,700 + 4,750) ÷ 100 = 9,150 ÷ 100 = 91.5 Note the plain mean of 90, 85, and 95 would be 90 — the weighting shifts the result because the highest-scoring item (the final) counts for half the grade.
Frequently asked questions
How do you find the average of a set of numbers?
Add all the numbers together, then divide by how many numbers there are. Five test scores of 85, 90, 78, 92, and 88 add up to 433; divided by 5, the average is 86.6.
What's the difference between average and median?
Average (mean) adds everything up and divides by the count. Median is the middle value once the numbers are sorted. They're usually close, but a few extreme values can pull the mean well away from what's "typical," while the median stays put — that's why the median is often the more representative figure for things like income or home prices.
What if there's no mode, or more than one?
If every value in the list appears exactly once, there's no mode — nothing stands out as more frequent than anything else. If two or more values are tied for the most frequent, the data set is multimodal, and all of the tied values are reported as modes.
How do I calculate a weighted average?
Multiply each value by its weight, add those products together, then divide by the total of all the weights. This gives more influence to values with larger weights, unlike a plain average which treats every value the same.
Can I paste numbers written with a comma as the decimal (e.g. "1,5")?
Not directly — commas are used to separate numbers in the list, so "1,5" is read as two values, 1 and 5, not one value of 1.5. If you're used to writing decimals with a comma, replace it with a period before pasting (1.5 instead of 1,5), or separate your numbers with spaces or new lines instead of commas.
Does the calculator accept scientific notation (like 1e3)?
No — enter the full number instead (1000 rather than 1e3). This matches how number entry works throughout the rest of the site.