An average calculator finds the arithmetic mean of a list of numbers by adding them and dividing by how many there are. The average of 10, 20, 30 and 40 is 100 ÷ 4 = 25.
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How to use the average calculator
- Type or paste your numbers, separated by commas.
- Run the calculator.
- Read the average (mean).
What is the average formula?
- Average (arithmetic mean) = sum of the values ÷ number of values
- Example: (10 + 20 + 30 + 40) ÷ 4 = 100 ÷ 4 = 25
The average calculator adds every number in the list and divides by how many there are. Negative numbers and decimals are fine; separate the values with commas.
Average calculator worked example
| Values | Count | Sum | Mean | Median |
|---|---|---|---|---|
| 10, 20, 30, 40 | 4 | 100 | 25 | 25 |
| 2, 4, 4, 5, 7, 9 | 6 | 31 | 5.167 | 4.5 |
| 85, 90, 78, 92, 88 | 5 | 433 | 86.6 | 88 |
| 1, 2, 3, 100 | 4 | 106 | 26.5 | 2.5 |
| 3.5, 4.25, 5 | 3 | 12.75 | 4.25 | 4.25 |
| -5, 0, 5, 10 | 4 | 10 | 2.5 | 2.5 |
Test scores of 85, 90, 78, 92 and 88 add up to 433. Divided by 5, the average is 86.6. The median, the middle value once the list is sorted, is 88.
Mean, median and mode
“Average” usually means the arithmetic mean, but there are other measures of the middle of a data set. The median is the middle value when the numbers are in order; with an even count it is the mean of the two middle values. The mode is the value that appears most often. In the list 2, 4, 4, 5, 7, 9 the mean is 5.17, the median is 4.5 and the mode is 4. When these three are close, the data are fairly balanced; when they are far apart, the data are skewed.
When the mean misleads
One extreme value can pull the mean a long way. For 1, 2, 3 and 100 the mean is 26.5, even though three of the four numbers are 3 or less; the median, 2.5, describes the typical value better. That is why incomes and house prices are often reported as medians. If your list has an outlier, compare the mean with the median before deciding which to report.
Weighted averages
A plain average gives every value the same weight. When some values count more, such as a final exam worth 50% of a grade or courses with different credit hours, use a weighted average: multiply each value by its weight, add the products and divide by the sum of the weights. Scores of 80 (weight 1) and 95 (weight 3) give (80 + 285) ÷ 4 = 91.25, while the simple average calculator result would be 87.5.
Tips for entering data
- Check for typing errors such as a missing decimal point, which can change the average sharply.
- Leave out blank or missing values rather than entering them as zero, unless zero is a real value.
- To average percentages or rates from groups of different sizes, weight each by its group size.
- Round only the final answer, not the values you enter.
Everyday uses for an average
Averages turn a list of numbers into a single figure that is easy to compare. Common uses include a class test average, average monthly spending on groceries or utilities, average fuel economy across several fill-ups, the average time a task takes, and average daily steps over a week. In each case, collect the values for the same period or group, paste them into the average calculator and compare the result with a target or with an earlier period.
Averages work best when the values measure the same thing in the same units. Averaging monthly bills is meaningful; averaging a monthly bill with a yearly one is not, unless you first convert both to the same period. Likewise, when you average speeds over equal distances, such as 30 mph out and 60 mph back, the true average speed is the total distance divided by total time, 40 mph, not the simple mean of 45. For rates like this the harmonic mean is the right tool, so think about what the numbers represent before you use the average calculator.
Related converters and calculators
Related calculators:
- Standard deviation calculator: spread
- Percentage calculator: percentages
- GPA calculator: grades
- Average return calculator: returns
Sources
NIST/SEMATECH e-Handbook: Measures of location; NIST/SEMATECH e-Handbook of Statistical Methods: Confidence limits for the mean.
Questions about this calculator
How do you calculate an average?
Add the values and divide by how many there are.
What is the average of 10, 20, 30 and 40?
25.
What is the difference between mean and median?
The mean uses every value; the median is the middle value.
When should I use a weighted average?
When some values count more than others.
Can I average negative numbers?
Yes. Include them with their minus sign.
Check the assumptions and units before relying on a result. Financial, tax and health estimates do not replace advice for your individual circumstances.
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