📊 Statistics Calculators

Standard deviation, z-scores, confidence intervals, p-values — the stats toolkit for students, researchers, and the statistically curious.

• Confidence Interval CalculatorConfidence interval and margin of error for a sample mean.
• Normal Distribution CalculatorBell curve probability — below, above, or between any values.
• P-Value CalculatorP-value from a z-score — two-tailed, left-tailed, or right-tailed.
• Standard Deviation CalculatorSample or population standard deviation from any list of numbers.
• Variance CalculatorSample or population variance, plus mean and standard deviation.
• Z-Score CalculatorHow many standard deviations from the mean — with percentile.