Average Calculator
Instantly calculate the mean, median, mode, range and standard deviation of a set of numbers, or work out a weighted average.
How to Use the Average Calculator
Our Average Calculator works out the mean, median, mode, range and standard deviation of any list of numbers, instantly and for free. Whether you’re averaging test scores, monthly expenses, sports statistics or a data set for a report, just paste your numbers in and get every common average and spread measure at once. Need to weight some values more heavily than others, such as exam grades split by percentage or portfolio returns by holding size? Switch to the Weighted Average tab.
What Is an Average?
“Average” usually refers to the mean: add up all the values in a set and divide by how many values there are. But there are several other measures of central tendency that describe a data set in different ways, and this calculator provides all of the common ones so you can compare them side by side.
| Measure | What It Shows | Best Used When |
|---|---|---|
| Mean (Average) | Sum of values divided by count | Data is evenly spread, no extreme outliers |
| Median | The middle value when sorted | Data has outliers or is skewed (e.g. salaries, house prices) |
| Mode | The most frequently occurring value | You want the most common or typical result |
| Range | Difference between highest and lowest value | You want a quick sense of spread |
| Standard Deviation | How spread out values are from the mean | You need a precise measure of variability |
How to Use the Average Calculator
- Simple Average: Type or paste your numbers into the box, separated by commas, spaces or new lines.
- Choose how many decimal places you want in the results.
- Click Calculate Average to see the mean, median, mode, range and standard deviation.
- Weighted Average: Switch tabs, then enter each value with its corresponding weight (e.g. a grade and its percentage weighting).
- Click Calculate Weighted Average to see the weighted result alongside the simple, unweighted average for comparison.
Mean vs Median vs Mode: Which Should You Use?
The mean is the most commonly used average, but it can be skewed by outliers. For example, if nine people earn £30,000 and one person earns £500,000, the mean salary looks much higher than what most people actually earn. The median is often more representative in cases like this, since it isn’t affected by extreme values. The mode is most useful when you want to know the single most common value in a set, such as the most frequently ordered product size.
What Is a Weighted Average?
A weighted average gives some values more influence over the result than others, based on an assigned weight. It’s calculated by multiplying each value by its weight, summing those products, and dividing by the total of all weights. This is common in academic grading (where coursework and exams are weighted differently), investment portfolios (where holdings are weighted by size), and business reporting (where figures are weighted by volume or importance). Our calculator also shows the simple average of the same values for comparison — this figure treats every entered value equally and includes all of them regardless of their weights, so you can see exactly how much the weighting changes the result.
Understanding Standard Deviation
- Population standard deviation is used when your numbers represent an entire data set (every value that exists), and divides by the total count (n).
- Sample standard deviation is used when your numbers are a sample taken from a larger population, and divides by one less than the count (n-1) to correct for sampling bias.
- A low standard deviation means values are clustered closely around the mean; a high standard deviation means they’re more spread out.
- If you’re not sure which to use, sample standard deviation is the safer default for survey or experimental data, while population standard deviation suits complete data sets like exam results for an entire class.
Frequently Asked Questions
How do you calculate an average?
To calculate a simple average (the mean), add up all the numbers in your data set, then divide by how many numbers there are. For example, the average of 4, 8 and 12 is (4 + 8 + 12) divided by 3, which equals 8.
What is the difference between mean, median and mode?
The mean is the sum of all values divided by the count. The median is the middle value when the data is sorted from smallest to largest. The mode is the value that appears most often. All three are types of average, but they can give different answers, especially when a data set has outliers.
How do you calculate a weighted average?
Multiply each value by its assigned weight, add up all of those results, then divide by the total of all the weights. This gives more influence to values with higher weights than a simple average would.
What if a data set has more than one mode?
A data set can have two or more modes if multiple values share the highest frequency, known as bimodal or multimodal. If every value appears the same number of times, there is no meaningful mode, and this calculator will show “No mode” in that case.
What is the difference between population and sample standard deviation?
Population standard deviation divides by the total count of values (n) and is used when your data covers an entire group. Sample standard deviation divides by one less than the count (n-1) and is used when your data is a sample drawn from a larger population, which corrects for the tendency of samples to underestimate true variability.
Why is my median different from my mean?
The mean and median differ when a data set is skewed by unusually high or low values. For example, most salaries in a company might cluster around £30,000, but one very high executive salary can pull the mean upward while the median stays closer to what most people actually earn.
Can I use negative or decimal numbers?
Yes, the calculator accepts negative numbers and numbers with decimal places. This is useful for data such as temperature changes, profit and loss figures, or scientific measurements.
What is a good use for the weighted average calculator?
Weighted averages are commonly used for calculating final exam grades where coursework and exams count differently, working out the average purchase price of shares bought at different prices and quantities, and combining survey results where some responses represent more people than others.