Average calculator

How to use the average calculator

1. Type your numbers in the box, or paste them: a list from a document, or a column copied from a spreadsheet.
2. Separate them with commas, spaces, semicolons or new lines. Use a point for decimals, like 12.5, and leave commas out of big numbers: write 1500, not 1,500, since a comma separates two numbers here.
3. The results change as you type, with your numbers in order under them.

Anything that isn’t a number, like a heading or “N/A”, is left out and listed under the box. A % after a number or a currency sign before it is fine. Press Clear to start again.

Mean, median and mode: one example

The box starts with a player’s points in six games: 3, 7, 2, 10, 3, 5.

Result	How it’s found	Answer
Mean	the sum, 30, divided by the count, 6	5
Median	in order, 2, 3, 3, 5, 7, 10: halfway between 3 and 5	4
Mode	the number that appears most often	3
Range	the largest, 10, minus the smallest, 2	8

Each is a fair answer to “how many points does the player usually score?”, but each tells you something different.

Which average to use

• The mean uses every number, so it’s the right one for totals: the mean spend a day times 30 gives the spend for a month. Use it when the numbers are fairly even.
• The median is the middle value: half the numbers are below it, half above. A few very large or very small values don’t move it, so it suits incomes, house prices and journey times.
• The mode is the most common value. It’s the one to use for sizes and choices: the shoe size a shop sells most, or the answer most people gave.

How one big number moves the mean

A small business pays five people 30000, 32000, 35000, 38000 and 40000 a year, and its owner 400000. Paste the six numbers into the box: the mean is about 95,833, more than five of the six earn. The median is 36,500, a better picture of a typical pay. When the mean and the median are far apart, a few values are pulling the mean their way.

A weighted average: working out a grade

When some parts count more than others, each one is multiplied by its weight. Say homework counts for 20% of a grade, a midterm for 30% and the final exam for 50%, and your scores are 85, 72 and 90:

• Homework: 85 × 0.2 = 17
• Midterm: 72 × 0.3 = 21.6
• Final exam: 90 × 0.5 = 45

Add them up: 17 + 21.6 + 45 = 83.6. The plain mean of the three scores is about 82.3, lower, because it counts the weaker midterm as much as the final.

Don’t average percentages

In one class, 9 of 10 students passed, 90%; in another, 20 of 40 passed, 50%. The mean of 90% and 50% is 70%, but the two classes together had 29 passes out of 50 students: 58%. Averaging percentages treats a class of 10 like a class of 40. Add up the counts first, then work out the percentage with the percentage calculator.