Statistics Calculator
Calculate mean, median, mode, standard deviation, and more from any data set.
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Frequently Asked Questions
What is the difference between mean, median, and mode?▼
Mean is the arithmetic average (sum ÷ count). Median is the middle value when sorted — resistant to outliers. Mode is the most frequently occurring value. For symmetric distributions they are similar; for skewed data they diverge significantly.
What is standard deviation?▼
Standard deviation measures how spread out values are from the mean. A low SD means values cluster near the mean; a high SD means they are spread out. About 68% of values fall within ±1 SD, 95% within ±2 SD (for normal distributions).
What is the difference between population and sample standard deviation?▼
Population SD divides by N (all data). Sample SD divides by N−1 (Bessel's correction) to produce an unbiased estimate when working with a subset. Use sample SD (N−1) when your data is a sample from a larger population.
What is variance?▼
Variance is the square of the standard deviation. It measures the average squared deviation from the mean. It is harder to interpret in original units (since it's squared), which is why standard deviation (the square root) is typically reported.