What the results mean
The mean is the usual average: the sum divided by how many numbers there are. The median is the middle number once the list is sorted (or the average of the two middle numbers), and it ignores extreme values, so it is better for things like salaries or house prices. The mode is the most common value; a list can have one, several or none. The range is the distance between the smallest and largest.
The standard deviation says how spread out the numbers are: a small one means they cluster close to the mean. Use the population version when your list is the whole group, and the sample version (dividing by n − 1) when it is a sample of a bigger group, which is the usual case in school and research. The quartiles split the sorted list into four parts; Q1 is the median of the lower half and Q3 the median of the upper half.
Questions
How do I enter numbers? Separate them with commas, spaces, semicolons or new lines, so you can paste a spreadsheet column. Anything that is not a number is listed and ignored. Why does a quartile differ from my textbook? There are several methods; this page uses the median-of-halves method taught in many schools. Is my data uploaded? No. Up to 100,000 numbers are handled in your browser. For percentages, see the Percentage Calculator.