Z-Score Calculator

About this calculator

The z-score standardizes a value against a distribution using z = (x − μ) ÷ σ, where μ is the mean and σ is the standard deviation — the result tells you how many standard deviations above or below average that value sits, positive for above and negative for below.

Statistics students use it to interpret test scores or survey data, quality-control engineers use it to flag measurements that fall outside a normal manufacturing tolerance, and researchers use it to compare values drawn from different scales (like exam results and lab measurements) on one common footing.