Statistics Calculator

The mean is the average (sum ÷ count). The median is the middle value when data is sorted — better for skewed distributions. The mode is the value that appears most often. For example, in {1, 2, 2, 3, 10}: mean = 3.6, median = 2, mode = 2.

Standard deviation measures how spread out values are from the mean. A low SD means data points cluster tightly around the mean; a high SD means they are widely spread. The calculator shows both population SD (σ, when your data is the whole population) and sample SD (s, when it's a sample from a larger population).

Use population standard deviation (σ) when your dataset contains every value in the group you're studying. Use sample standard deviation (s) — which uses n−1 in the denominator (Bessel's correction) — when your data is a sample taken from a larger population, which is most common in research.

Quartiles divide sorted data into four equal parts. Q1 (the 25th percentile) is the median of the lower half; Q3 (75th percentile) is the median of the upper half. The IQR (Interquartile Range) = Q3 − Q1 and measures the spread of the middle 50% of data, making it robust to outliers.

Paste your numbers separated by commas, spaces, or new lines — the calculator accepts all formats. For example: "12, 15, 18, 22, 9" or one number per line. Non-numeric values are automatically ignored.