Average Calculator vs Standard Deviation Calculator

Mean is the sum divided by the count (arithmetic average). Median is the middle value when sorted. Mode is the most frequent value. Each measures central tendency differently.

Use median when data has outliers or is skewed. For example, median household income is more representative than mean income because a few very wealthy people skew the mean upward.

Standard deviation measures the spread or variability in a dataset — how far individual values typically stray from the mean. A small standard deviation means values cluster tightly around the average. A large one means they're spread out widely. It's the most widely used measure of statistical dispersion.

Use population standard deviation (σ, divides by N) when you have data for the entire group you're studying. Use sample standard deviation (s, divides by N-1) when your data is a sample drawn from a larger population — the N-1 correction (Bessel's correction) produces an unbiased estimate. In practice, you almost always use sample standard deviation.