Statistics calculators

Z-scores, confidence intervals, event probabilities and weighted averages, with the assumptions behind each one stated.

Confidence interval calculator

Find the margin of error and the interval around a sample mean when σ is known.

Find the chance of not A, of A and B, or of A or B from event probabilities.

Average values that count unequally, such as graded coursework.

See how many standard deviations a value lies above or below the mean.