Write the values
Begin with the complete set: 10, 20, 30, and 40.
Math calculator
All CalculatorsAverage Calculator
Enter a list of numbers to calculate the arithmetic mean, total, count, median, mode, range, minimum, and maximum.
Interactive calculator
Calculate the average of your numbers
Separate values with commas, spaces, or new lines. Negative numbers and decimals are supported.
Interactive distribution
See how your values compare with the average
Each bar represents one value. The horizontal line marks the arithmetic mean of the complete set.
What the result means
How is an average calculated?
The arithmetic mean is found by adding all values and dividing the total by the number of values.
It represents the amount each value would have if the total were redistributed equally across the set.
Average formula
Sum of the values divided by the number of values
Add every number in the list. Count how many numbers were entered, then divide the total by that count.
Arithmetic meanAverage = Sum ÷ Count
Example
(10 + 20 + 30 + 40) ÷ 4 = 25
Worked method
Average calculation step by step
Follow these four steps when calculating an arithmetic mean manually.
Add the numbers
10 + 20 + 30 + 40 gives a total of 100.
Count the values
There are four numbers in the list.
Divide the sum
Divide 100 by 4. The average is 25.
Final calculation100 ÷ 4 = 25
Equal sharing
The average redistributes the same total equally
The values 4, 8, 10, and 14 have a total of 36. Dividing 36 equally between four values gives 9.
The total does not change. Only the distribution becomes equal.
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Same total→Shared equally
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Central values
Mean, median, mode, and range
These measures describe a group of numbers in different ways.
The total of all values divided by the number of values.
The centre value after arranging the numbers in order.
The value or values appearing most often in the list.
The distance between the highest and lowest values.
Outlier effect
One extreme value can move the average
The values 10, 11, 12, 13, and 14 have an average of 12. Replacing 14 with 100 increases the average to 29.2.
The median changes much less, which is why it can be more representative when a set contains extreme values.
Balanced setAverage: 12
With an outlierAverage: 29.2
Different average methods
Simple average, weighted average, and average percentage
Not every situation should use the same averaging method.
Every value has equal importance
Add the values and divide by the count. This is the calculation performed by the main tool above.
Some values contribute more
Multiply each value by its weight, add the weighted results, and divide by the total weight.
Check whether the bases are equal
Percentages can be averaged directly only when they represent comparable totals or equal weighting.
Reverse calculation
Find a missing number from a known average
Multiply the required average by the total number of values. Subtract the sum of the known values to find the missing one.
Example
Average of four numbers:20
Required total:20 × 4 = 80
Known values:10 + 15 + 25 = 50
Missing number:80 − 50 = 30
Avoid incorrect results
Common average-calculation mistakes
Using the wrong count
Divide by the number of values, not by the largest number or the number of spaces between values.
Ignoring different weights
A simple average is not correct when some values carry more importance than others.
Averaging unequal percentages
Percentages based on different totals may need a combined weighted calculation.
Ignoring outliers
One extreme value can pull the arithmetic mean away from the typical values in the set.
Continue calculating
Related calculators
Use these tools for percentages, change, fractions, and ratios.
Average Calculator guides
Learn more about averages
Read detailed explanations, formulas, and worked examples for common average calculations.
Core calculationHow to Calculate the Average of Numbers
Learn the complete arithmetic-mean method with examples.
Formula guideAverage Formula ExplainedUnderstand how the sum and number of values determine the mean.
Two valuesHow to Find the Average of Two NumbersFind the midpoint between two numerical values.
Multiple valuesHow to Find the Average of Three or More NumbersAdd a complete set and divide by the number of observations.
ComparisonMean vs MedianUnderstand which measure of the centre is more representative.
Data interpretationHow Outliers Affect the AverageSee how an unusually high or low value can move the mean.
Advanced methodHow to Calculate a Weighted AverageGive different values different levels of importance.
Percentage valuesHow to Calculate an Average PercentageAverage percentages correctly when their contributions are equal.
Grade calculationHow to Calculate an Average GradeCalculate equal-weight, point-based, and weighted grades.
Reverse calculationFind a Missing Number from an AverageWork backwards from the required arithmetic mean.
Frequently asked questions
Average Calculator FAQs
What is an arithmetic mean?
It is the sum of all values divided by the number of values.
Is average the same as mean?
In ordinary arithmetic, average commonly refers to the arithmetic mean.
Can I enter decimal numbers?
Yes. The calculator accepts positive numbers, negative numbers, integers, and decimals.
Can a list have more than one mode?
Yes. When multiple values share the highest frequency, the calculator reports all of them.
What happens when every value appears once?
The list has no mode because no value occurs more often than the others.
Why can the mean and median be different?
The mean uses every value and can be affected by outliers, while the median depends on the middle position.
Can I average percentages?
Percentages may be averaged directly when their bases and weights are comparable. Otherwise, use a weighted method.
How do I calculate a weighted average?
Multiply each value by its weight, add the products, and divide by the total of the weights.
Can the average be outside the value range?
A simple arithmetic mean cannot be lower than the minimum or higher than the maximum value.
Does the order of the numbers matter?
No. Rearranging the values does not change their sum, count, or arithmetic mean.
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Use Average CalculatorFind the average of your numbers
Enter your list to see the mean and the complete statistical summary.