How to calculate an average age: 9 steps

How to calculate an average age: 9 steps
How to calculate an average age: 9 steps

Did you know that it is very easy to calculate the average age of a given group of people? The mean is very useful, but sometimes you need to use another value that is representative of a sample or an entire population.


Part 1 of 3: Calculate an average age

Calculate Average Age Step 1

Step 1. List the people with their respective ages

Calculating an average is ultimately very simple. The first step is to make a list of all the items that you want to average. You can either write them down on a piece of paper or type them into a spreadsheet.

Calculate Average Age Step 2

Step 2. Sum all the ages in your sample

Adding up means adding them all up without forgetting any. Suppose you have a group of five people whose ages are: 31, 30, 26, 21, and 10. The total of all these ages is therefore 118 years.

Calculate Average Age Step 3

Step 3. Divide the sum obtained by the number of the series

The latter is the number of ages you have added up. The result of the division in question is the average age. If we take the previous example, we therefore had a sum of 118 years, which we will divide by the number of people in the group, i.e. 5. The average age of the group is: 118/5, or 23, 6 years old.

What is valid for a group of 5 people is also for a much larger group (100, 300, 1500 people…) To prove it, let's take the example of a tennis club with 100 registered members. Since you are everyone's age, you add them all up, then divide the result by the number of members, or 100. This gives you the average age of club members

Calculate Average Age Step 4

Step 4. Find the mean of other data sets

What we have just done with ages can be done with other types of data, like annual profits, monthly stadium entries, etc., the principle is always the same.

  • So, let's say you want to know the average population of the top ten French cities. You need to collect the populations of each of them, add them up, then divide them by 10 and you will have the result you want.
  • There may be times when you need to calculate a weighted average. At school, all homework does not necessarily have the same importance, some are more difficult and therefore have a higher coefficient. To calculate the average, multiply each score by its coefficient, add it all up, then divide by the total of the coefficients.

Part 2 of 3: know when to use an average

Calculate Average Age Step 5

Step 1. Differentiate between an average and the median

It often happens that people confuse these two terms in favor of the average. For some analyzes, the median of a series of numbers is much more relevant than the mean.

  • The median of a data series is the value that is at the center of the data set. Clearly, there are as many values ​​below and beyond this central value.
  • The median is much more relevant than the average if in your age range there is an extreme value. Take the example of a BTS class with 19 students aged 18 to 25. However, this class is special, because there is a twentieth student who is… 80 years old. You understand that the average for that class will be pulled up because of this particular student, so the average doesn't really represent the class. If you are looking for the median age, then you will have a much better representation of the age of the students. Consequently, as soon as in a series you have an out-of-range value, use the median instead.
Calculate Average Age Step 6

Step 2. Know that the mode is a value that differs from the average

The mode of a data series is the value that occurs most frequently in the series.

  • For a given series, there are many values ​​that can represent it (mean, median, mode). Depending on the case, you should use one or the other to make your job easier.
  • If you are asked to calculate an average age while being given age groups (e.g. people between 2 and 4 years old, 4 and 6 years old, etc.), you calculate the value center of each interval, you multiply that value by the class size. You add up all of your results and divide by the total number of people.

Part 3 of 3: Calculate the average age of a large number of people

Calculate Average Age Step 7

Step 1. Consider using an Excel spreadsheet

If you have to calculate an average with a very large number of ages, your best bet is to use Excel. Of course, you can do the calculations with a calculator and write them down on a piece of paper, but it will take longer.

  • Suppose you need to calculate the average age of all students in a high school or all employees of a large company. Then you understand why, with several hundred people, you need a spreadsheet (Excel, not to name it), to be able to find the right answer.
  • The first thing to do is to enter all the ages in the worksheet. Excel is one of the programs in the Microsoft Office software suite. Several scenarios can happen: either you enter your data one after the other or you import it (copy / paste) from another document, the ideal being to have your ages already in an Excel spreadsheet.
  • To import a text file into Excel, click From text in the game External data. Excel, thanks to its import wizard, will transfer all your data into a spreadsheet.
Calculate Average Age Step 8

Step 2. Use the Excel mean formula

A worksheet is made up of columns (vertical) and rows (horizontal). We will take a group of 200 people and all the ages will be put in column A. The first age will be on line 1 and the last on line 200. Excel is able to calculate the average of all these ages provided you use a formula that you would put, for example, in cell A201.

  • The formula in Excel used to calculate the average is: = AVERAGE (A1: A200). In parentheses, you will first put the reference of the first numbered cell in column A, i.e. A1. You will put two points, then the reference of the last encrypted cell of this same column, that is to say A200.
  • In our example, you have to put A200, because the last age is in column A in row 200. The colon that separates the references of the two extreme cells are there to mean that all the values ​​in the column (A1, A200 and all those in) must be added, then divided by 200. With the formula entered correctly, press the key. Entrance and thus you will have the average.
Calculate Average Age Step 9

Step 3. Use online average calculators

Indeed, there are sites on the Internet that calculate the average of a series of numbers for you, you just have to enter your numbers, often in a certain way.

Of course, you can also work "the old fashioned way" with pen, paper and a calculator. Once you understand how to calculate an average, you can choose the method that you like the most


While it is very safe, keep a copy of your data (on paper or in a text file). Thus, you are protected against any loss of data if the computer (or software) should have a problem


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